Regeneration of dental-pulp-like tissue by chemotaxis-induced cell homing

Dental Pulp Regeneration in Dogs Using a Chemokine Receptor 3 Antagonist Without Transplantation of Dental Pulp Stem Cells

INTRODUCTION

Our previous study showed that transplantation of dental pulp stem cells in combination with a chemokine receptor 3 (CCR3) antagonist into the root canals of aged dogs promoted dental pulp regeneration. In this study, we attempted to regenerate dental pulp in young dogs using a CCR3 antagonist without dental pulp stem cell transplantation.

METHODS

The teeth of dogs were histologically evaluated 4 weeks after extraction of the pulp and administration of scaffold materials and CCR3 antagonist (KDH-136) into the root canal. The effects of KDH-136 on the inflammatory response of RAW264.7 cells were investigated in vitro. In addition, we also examined whether KDH-136 affected neurite outgrowth of PC12 cells.

RESULTS

Application of KDH-136 resulted in the formation of dental pulp-like tissue. Furthermore, nerve and blood vessel regeneration were observed. KDH-136 suppressed chemokine production from RAW264.7 cells and promoted nerve growth factor-stimulated neurite outgrowth of PC12 cells.

CONCLUSIONS

CCR3 antagonists may be useful for developing novel methods of dental pulp regeneration that do not require transplantation of dental pulp stem cells.

Engineering soft-hard tissue interfaces in dental and craniofacial system by spatially controlled bioactivities

The interface between soft and hard tissues is constituted by a gradient change of cell types and matrix compositions that are optimally designed for proper load transmission and injury protection. In the musculoskeletal system, the soft-hard tissue interfaces at tendon-bone, ligament-bone, and meniscus-bone have been extensively researched as regenerative targets. Similarly, extensive research efforts have been made to guide the regeneration of multi-tissue complexes in periodontium. However, the other soft-hard tissue interfaces in the dental and craniofacial system have been somewhat neglected. This review discusses the clinical significance of developing regenerative strategies for soft-hard tissue interfaces in the dental and craniofacial system. It also discusses the research progress in the field focused on bioengineering approaches using 3D scaffolds equipped with spatially controlled bioactivities. The remaining challenges, future perspectives, and considerations for the clinical translation of bioactive scaffolds are also discussed.

Cell Homing Strategies in Regenerative Endodontic Therapy

Cell homing, a process that leverages the body's natural ability to recruit cells and repair damaged tissues, presents a promising alternative to cell transplantation methods. Central to this approach is the recruitment of endogenous stem/progenitor cells-such as those from the apical papilla, bone marrow, and periapical tissues-facilitated by chemotactic biological cues. Moreover, biomaterial scaffolds embedded with signaling molecules create supportive environments, promoting cell migration, adhesion, and differentiation for the regeneration of the pulp-dentin complex. By analyzing in vivo animal studies using cell homing strategies, this review explores how biomolecules and scaffold materials enhance the recruitment of endogenous stem cells to the site of damaged dental pulp tissue, thereby promoting repair and regeneration. It also examines the key principles, recent advancements, and current limitations linked to cell homing-based regenerative endodontic therapy, highlighting the interplay of biomaterials, signaling molecules, and their broader clinical implications.

Clinical and radiographic evaluation of two different apexification protocols in traumatized immature permanent incisors

BACKGROUND

Dental trauma can cause damage to the pulp tissue in immature teeth. Revascularization therapy is a possible option in the treatment of non-vital, immature permanent teeth with a history of trauma. The aim of this prospective study was to evaluate the radiographic and clinical results of immature teeth with a history of trauma treated by regenerative endodontic procedures and mineral trioxide aggregate apexification techniques.

METHODS

Forty-one patients aged between 7 and 12 years with traumatized immature permanent maxillary incisors were included in the study. These patients were divided into two groups: those who had previously received endodontic treatment and those who had not. Twenty-four patients who applied directly to the university clinic and had not received endodontic treatment before were included in the regenerative endodontic protocol group (Group 1). Seventeen patients who had previously undergone endodontic intervention on their relevant teeth were included in the mineral trioxide aggregate apexification group (Group 2). The patients were followed for a period of 24 months. Clinical success rates were evaluated, and pre-treatment and control radiographs were analyzed to calculate the percentage increase in root dentin width and root length.

RESULTS

After 24 months of follow-up, positive periapical healing was detected in the radiographic findings in the majority of cases. In Group 1, a limited increase in root length and root dentin width was observed, while a narrowing in the apical opening was evident. The radiographic evaluation of two of the cases, which could be accessed 11 years later, emphasized the importance of long-term follow-up in assessing the effectiveness of the chosen methods.

CONCLUSION

The revascularization method is a treatment option that has positive results in terms of root development in teeth with necrotic pulp as a result of trauma.

A Comparison Between Three Types of Scaffolds for Pulp Regeneration: A Histological Study on Dogs

OBJECTIVES

This study aims to compare the application of three types of normal scaffolds-native chitosan, enzymatically modified chitosan, and blood clot (BC)-on pulp regeneration in the teeth of experimental dogs through histological examination, to determine the quantity and type of new tissues formed within the root canal.

MATERIALS AND METHODS

The research sample consisted of 32 root canals from 20 premolars of two male local experimental dogs. The sample was randomly divided into a control group, in which no intervention was performed on the teeth, and three experimental groups based on the type of scaffold used: the BC group, the native chitosan combined with BC (NCS + BC) group, and the enzymatically modified chitosan combined with BC (EMCS + BC) group. Mechanical and chemical cleaning of the canals was performed, followed by the application of the studied scaffolds within the root canals. After 3 months, the teeth were extracted and prepared for histological study, where two variables were studied: the percentage of total vital tissue (soft and hard; VT%) and the percentage of soft vital tissue only (ST%). A one-way ANOVA and Bonferroni tests were used to determine significant differences between the groups at a 95% confidence level.

RESULTS

The VT% values were significantly higher in the EMCS + BC group compared to both the NCS + BC and BC groups. The ST% values were also significantly higher in the EMCS + BC group compared to the BC group. However, no significant differences in ST% values were observed between the NCS + BC group and either the BC or EMCS + BC groups.

CONCLUSIONS

Within the limitations of this study, we conclude that the application of enzymatically modified chitosan scaffolds combined with BC yields superior results in pulp regeneration, which contributes to the formation of pulp-like tissue and cells resembling odontoblasts, as well as apex closure with tissue resembling bone tissue.

Enhancing Gingival-Derived Mesenchymal Stem Cell Potential in Tissue Engineering and Regenerative Medicine Through Paraprobiotics

Gingival-derived mesenchymal stem cells (GMSCs) stand for a unique source of mesenchymal stem cells (MSCs) isolated from a neural crest origin with potential application in regenerative medicine. However, there are some limitations to the usage of these cells in clinical cell therapy such as reduced cell number and undesirable differentiation of the cell throughout frequent passages. Nowadays, studies have applied manipulation strategies to improve MSCs' effectiveness in clinical therapy. Among all of the materials used for this purpose, there is a growing trend for the use of biomaterials such as probiotic extracts or their conditioned media due to their lower toxicity. In the present study, we utilized extracts from Lactobacillus reuteri and Lactobacillus rhamnosus to assess their potential to enhance the function of GMSCs. We compared the effectiveness of these bacterial extracts to determine their relative efficacy. Bacterial extracts of two lactic acid bacteria were prepared using an ultrasonic homogenizing device. The impact of these bacterial extracts on GMSCs was evaluated through Alizarin Red and Oil Red O staining, cell counting by Trypan Blue staining, and real-time polymerase chain reaction. The findings of our study indicate that the administration of 50 μg/mL L. rhamnosus extract resulted in a greater enhancement of stemness marker expression, osteogenic differentiation, and proliferation of GMSCs compared with an equivalent concentration of L. reuteri extract. Neither of these bacterial extracts revealed any effect on the differentiation of the GMSCs into the adipogenic lineage. These findings suggest that L. rhamnosus extract could be more effective at promoting GMSCs' efficacy in tissue engineering and regenerative medicine.

Preparation and characterization of bovine dental pulp-derived extracellular matrix hydrogel for regenerative endodontic applications: an in vitro study

BACKGROUND

The use of biological scaffolds in regenerative endodontics has gained much attention in recent years. The search for a new biomimetic scaffold that contains tissue-specific cell homing factors could lead to more predictable tissue regeneration. The aim of this study was to prepare and characterize decellularized bovine dental pulp-derived extracellular matrix (P-ECM) hydrogels for regenerative endodontic applications.

METHODS

Freshly extracted bovine molar teeth were collected. Bovine dental pulp tissues were harvested, and stored at -40º C. For decellularization, a 5-day protocol was implemented incorporating trypsin/EDTA, deionized water and DNase treatment. Decellularization was evaluated by DNA quantification and histological examination to assess collagen and glycosaminoglycans (GAGs) content. This was followed by the preparation of P-ECM hydrogel alone or combined with hyaluronic acid gel (P-ECM + HA). The fabricated scaffolds were then characterized using protein quantification, hydrogel topology and porosity, biodegradability, and growth factor content using Enzyme-linked immunosorbent assay (ELISA): transforming growth factor beta-1(TGF-β1), basic fibroblast growth factor (bFGF), bone morphogenetic protein 2 (BMP-2) and vascular endothelial growth factor (VEGF).

RESULTS

Decellularization was histologically confirmed, and DNA content was below (50 ng/mg tissue). P-ECM hydrogel was prepared with a final ECM concentration of 3.00 mg/ml while P-ECM + HA hydrogel was prepared with a final ECM concentration of 1.5 mg/ml. Total protein content in P-ECM hydrogel was found to be (439.0 ± 123.4 µg/µl). P-ECM + HA showed sustained protein release while the P-ECM group showed gradual decreasing release. Degradation was higher in P-ECM + HA which had a significantly larger fiber diameter, while P-ECM had a larger pore area percentage. ELISA confirmed the retention and release of growth factors where P-ECM hydrogel had higher BMP-2 release, while P-ECM + HA had higher release of TGF-β1, bFGF, and VEGF.

CONCLUSIONS

Both P-ECM and P-ECM + HA retained their bioactive properties demonstrating a potential role as functionalized scaffolds for regenerative endodontic procedures.

Tissue engineering approaches for dental pulp regeneration: The development of novel bioactive materials using pharmacological epigenetic inhibitors

The drive for minimally invasive endodontic treatment strategies has shifted focus from technically complex and destructive root canal treatments towards more conservative vital pulp treatment. However, novel approaches to maintaining dental pulp vitality after disease or trauma will require the development of innovative, biologically-driven regenerative medicine strategies. For example, cell-homing and cell-based therapies have recently been developed in vitro and trialled in preclinical models to study dental pulp regeneration. These approaches utilise natural and synthetic scaffolds that can deliver a range of bioactive pharmacological epigenetic modulators (HDACis, DNMTis, and ncRNAs), which are cost-effective and easily applied to stimulate pulp tissue regrowth. Unfortunately, many biological factors hinder the clinical development of regenerative therapies, including a lack of blood supply and poor infection control in the necrotic root canal system. Additional challenges include a need for clinically relevant models and manufacturing challenges such as scalability, cost concerns, and regulatory issues. This review will describe the current state of bioactive-biomaterial/scaffold-based engineering strategies to stimulate dentine-pulp regeneration, explicitly focusing on epigenetic modulators and therapeutic pharmacological inhibition. It will highlight the components of dental pulp regenerative approaches, describe their current limitations, and offer suggestions for the effective translation of novel epigenetic-laden bioactive materials for innovative therapeutics.

Dental pulp regeneration strategies: A review of status quo and recent advances

Microorganisms, physical factors such as temperature or mechanical injury, and chemical factors such as free monomers from composite resin are the main causes of dental pulp diseases. Current clinical treatment methods for pulp diseases include the root canal therapy, vital pulp therapy and regenerative endodontic therapy. Regenerative endodontic therapy serves the purpose of inducing the regeneration of new functional pulp tissues through autologous revascularization or pulp tissue engineering. This article first discusses the current clinical methods and reviews strategies as well as the research outcomes regarding the pulp regeneration. Then the in vivo models, the prospects and challenges for regenerative endodontic therapy were further discussed.

Correlation between tooth decay and insulin resistance in normal weight males prompts a role for myo-inositol as a regenerative factor in dentistry and oral surgery: a feasibility study

Background

In an era of precision and stratified medicine, homogeneity in population-based cohorts, stringent causative entry, and pattern analysis of datasets are key elements to investigate medical treatments. Adhering to these principles, we collected in vivo and in vitro data pointing to an insulin-sensitizing/insulin-mimetic effect of myo-inositol (MYO) relevant to cell regeneration in dentistry and oral surgery. Confirmation of this possibility was obtained by in silico analysis of the relation between in vivo and in vitro results (the so-called bed-to-benchside reverse translational approach).

Results

Fourteen subjects over the 266 screened were young adult, normal weight, euglycemic, sedentary males having normal appetite, free diet, with a regular three-times-a-day eating schedule, standard dental hygiene, and negligible malocclusion/enamel defects. Occlusal caries were detected by fluorescence videoscanning, whereas body composition and energy balance were estimated with plicometry, predictive equations, and handgrip. Statistically significant correlations (Pearson r coefficient) were found between the number of occlusal caries and anthropometric indexes predicting insulin resistance (IR) in relation to the abdominal/visceral fat mass, fat-free mass, muscular strength, and energy expenditure adjusted to the fat and muscle stores. This indicated a role for IR in affecting dentin reparative processes. Consistently, in vitro administration of MYO to HUVEC and Swiss NIH3T3 cells in concentrations corresponding to those administered in vivo to reduce IR resulted in statistically significant cell replication (ANOVA/Turkey tests), suggesting that MYO has the potential to counteract inhibitory effects of IR on dental vascular and stromal cells turnover. Finally, in in silico experiments, quantitative evaluation (WOE and information value) of a bioinformatic Clinical Outcome Pathway confirmed that in vitro trophic effects of MYO could be transferred in vivo with high predictability, providing robust credence of its efficacy for oral health.

Conclusion

Our reverse bed-to-benchside data indicate that MYO might antagonize the detrimental effects of IR on tooth decay. This provides feasibility for clinical studies on MYO as a regenerative factor in dentistry and oral surgery, including dysmetabolic/aging conditions, bone reconstruction in oral destructive/necrotic disorders, dental implants, and for empowering the efficacy of a number of tissue engineering methodologies in dentistry and oral surgery.

Regenerative endodontic therapy: From laboratory bench to clinical practice

BACKGROUND

Maintaining the vitality and functionality of dental pulp is paramount for tooth integrity, longevity, and homeostasis. Aiming to treat irreversible pulpitis and necrosis, there has been a paradigm shift from conventional root canal treatment towards regenerative endodontic therapy.

AIM OF REVIEW

This extensive and multipart review presents crucial laboratory and practical issues related to pulp-dentin complex regeneration aimed towards advancing clinical translation of regenerative endodontic therapy and enhancing human life quality.

KEY SCIENTIFIC CONCEPTS OF REVIEW

In this multipart review paper, we first present a panorama of emerging potential tissue engineering strategies for pulp-dentin complex regeneration from cell transplantation and cell homing perspectives, emphasizing the critical regenerative components of stem cells, biomaterials, and conducive microenvironments. Then, this review provides details about current clinically practiced pulp regenerative/reparative approaches, including direct pulp capping and root revascularization, with a specific focus on the remaining hurdles and bright prospects in developing such therapies. Next, special attention was devoted to discussing the innovative biomimetic perspectives opened in establishing functional tissues by employing exosomes and cell aggregates, which will benefit the clinical translation of dental pulp engineering protocols. Finally, we summarize careful consideration that should be given to basic research and clinical applications of regenerative endodontics. In particular, this review article highlights significant challenges associated with residual infection and inflammation and identifies future insightful directions in creating antibacterial and immunomodulatory microenvironments so that clinicians and researchers can comprehensively understand crucial clinical aspects of regenerative endodontic procedures.

Heparin-Functionalized Bioactive Glass to Harvest Endogenous Growth Factors for Pulp Regeneration

Pulp and periapical diseases can lead to the cessation of tooth development, resulting in compromised tooth structure and functions. Despite numerous efforts to induce pulp regeneration, effective strategies are still lacking. Growth factors (GFs) hold considerable promise in pulp regeneration due to their diverse cellular regulatory properties. However, the limited half-lives and susceptibility to degradation of exogenous GFs necessitate the administration of supra-physiological doses, leading to undesirable side effects. In this research, a heparin-functionalized bioactive glass (CaO-P2O5-SiO2-Heparin, abbreviated as PSC-Heparin) with strong bioactivity and a stable neutral pH is developed as a promising candidate to addressing challenges in pulp regeneration. Fourier transform infrared spectroscopy, X-ray photoelectron spectroscopy, and thermogravimetric analysis reveal the successful synthesis of PSC-Heparin. Scanning electron microscopy and X-ray diffraction show the hydroxyapatite formation can be observed on the surface of PSC-Heparin after soaking in simulated body fluid for 12 h. PSC-Heparin is capable of harvesting various endogenous GFs and sustainably releasing them over an extended duration by the enzyme-linked immunosorbent assay. Cytological experiments show that developed PSC-Heparin can facilitate the adhesion, migration, proliferation, and odontogenic differentiation of stem cells from apical papillae. Notably, the histological analysis of subcutaneous implantation in nude mice demonstrates PSC-Heparin is capable of promoting the odontoblast-like layers and pulp-dentin complex formation without the addition of exogenous GFs, which is vital for clinical applications. This work highlights an effective strategy of harvesting endogenous GFs and avoiding the involvement of exogenous GFs to achieve pulp-dentin complex regeneration, which may open a new horizon for regenerative endodontic therapy.

Evaluation of the efficacy of injectable platelet-rich fibrin versus platelet-rich plasma in the regeneration of traumatized necrotic immature maxillary anterior teeth: A randomized clinical trial

BACKGROUND/AIM

This study aimed at comparing the regenerative potential of injectable platelet-rich fibrin (i-PRF) (Group 1) and platelet-rich plasma (Group 2) scaffolds.

MATERIALS AND METHODS

Twenty-three patients, aged from 9 to 24 years, having 24 immature traumatized necrotic maxillary anterior teeth, were enrolled. Teeth trauma was confirmed by patients' history. Preoperative three-dimensional scans were done. In the first visit, canals were irrigated with 1.5% sodium hypochlorite then medicated with calcium hydroxide. After 2 weeks, patients were randomly assigned into one of the treatment groups (n = 12). The platelet concentrate was applied after centrifuging 10 mL of autologous venous blood with respect to the centrifugation protocol for each platelet concentrate. Patients were recalled at 6 and 12 months posttreatment, during which clinical and radiographic examinations and assessment of pulp sensitivity were done. Three-dimensional scanning was done after 12 months. The increase in root length and decrease in root canal diameters were calculated at three canal levels. Statistical analysis was done using the paired t-test and the independent t-test. The significance level was set at p < .05.

RESULTS

There was no statistically significant difference between both groups regarding the increase in root length, decrease in coronal and middle canal diameters and the response to the electric pulp tester. Group (1) showed significantly greater decrease in apical canal diameter than Group (2) (p = .008).

CONCLUSION

I-PRF can be considered as a valid regenerative scaffold for clinical use and with regards to the easier preparation technique, it is more recommended than platelet-rich plasma.

Interactions of Neuronally Induced Stem Cells from Apical Papilla Spheres, Stems Cells from Apical Papilla, and Human Umbilical Vascular Endothelial Cells on Vasculogenesis and Neurogenesis

INTRODUCTION

Stem cell-based dental pulp regeneration has been extensively studied, mainly focusing on exploiting dental stem cells' osteogenic and angiogenic potentials. Dental stem cells' neurogenic role is often overlooked. Stem cells from apical papilla (SCAPs), originating from the neural crest and capable of sphere formation, display potent neurogenic capacity. This study aimed to investigate the interactions of neuronally induced stem cells from apical papilla (iSCAP) spheres, SCAPs, and human umbilical vascular endothelial cells (HUVECs) on vasculogenesis and neurogenesis.

METHODS

SCAPs were isolated and characterized using flow cytometry and multilineage differentiation assays. SCAP monolayer culture and spheres were neuronally induced by a small molecule neural induction medium, and the neural gene expression and neurite formation at days 0, 3, and 7 were evaluated by reverse transcription-quantitative polymerase chain reaction (RT-qPCR) and using phase-contrast light and fluorescence microscopy. Direct coculture or pulp-on-chip was used to investigate iSCAP sphere interaction with SCAPs and HUVECs. RT-qPCR, fluorescence microscopy, and immunostaining with β-tubulin III, alpha-smooth muscle actin, and CD31 were used to study neural gene expression, neurite formation, and neurovascular cell interactions.

RESULTS

Neural induction medium with small molecules rapidly induced SCAP differentiation toward neural-like cells. Gene expression of Nestin, β-tubulin III, microtubule-associated protein 2, neuron-specific enolase, and NeuN was higher in iSCAP spheres than in iSCAPs. iSCAP spheres formed more and longer neurites compared with iSCAPs. iSCAP sphere, HUVEC, and SCAP direct coculture significantly enhanced vessel formation along with up-regulated VEGF (P < .001) and multiple neural markers, such as Nestin (P < .01), microtubule-associated protein 2 (P < .001), S100 (P < .001), and NG2 (P < .001). iSCAP spheres, SCAPs, and HUVECs cultured in a pulp-on-chip system promoted endothelial and neural cell migration toward each other and alpha-smooth muscle actin-positive and CD31-positive cells assembling for the vascular constitution.

CONCLUSIONS

iSCAP-formed spheres interact with SCAPs and HUVECs, promoting vasculogenesis and neurogenesis.

Methylenetetrahydrofolate reductase polymorphisms in dental caries-induced pulp inflammation and regeneration of dentine-pulp complex: Future perspectives

Dental caries (DC)-induced pulp infections usually undergo the common endodontic treatment, root canal therapy (RCT). Endodontically treated teeth are devitalized, become brittle and susceptible for re-infection which eventually results in dental loss. These complications arise because the devitalized pulp losses its ability for innate homeostasis, repair and regeneration. Therefore, restoring the vitality, structure and function of the inflamed pulp and compromised dentin have become the focal points in regenerative endodontics. There are very few evidences, so far, that connect methylenetetrahydrofolate reductase single nucleotide polymorphisms (MTHFR-SNPs) and dental disorders. However, the primary consequences of MTHFR-SNPs, in terms of excessive homocysteine and folate deficiency, are well-known contributors to dental diseases. This article identifies the possible mechanisms by which MTHFR-SNP-carriers are susceptible for DC-induced pulp inflammation (PI); and discusses a cell-homing based strategy for in vivo transplantation in an orthotopic model to regenerate the functional dentine-pulp complex which includes dentinogenesis, neurogenesis and vasculogenesis, in the SNP-carriers.

Pulp Revascularization in an Autotransplanted Mature Tooth: Visualization with Magnetic Resonance Imaging and Histopathologic Correlation

Autotransplantation of a mature tooth usually leads to pulpal necrosis. Root canal treatment is recommended to prevent related inflammatory complications a few weeks after surgery. Extraoral root-end resection may facilitate reperfusion and obviate root canal treatment, but cannot be pictured with conventional dental radiography at this point in time. In the case of a lower mature transplanted molar, contrast-enhanced magnetic resonance imaging proved to be a feasible method for visualizing pulp revascularization just 4 weeks after autotransplantation. Consequently, root canal treatment was obviated. Nevertheless, the tooth had to be extracted 18 months postoperatively due to external cervical root resorption, probably caused by the extraction trauma. This allowed the histological processing and examination of the newly generated intracanal tissue. Uninflamed fibrovascular connective tissue was found, while odontoblasts or cementoblast-like cells were absent. These findings indicated that it was most likely stem cells from the bone marrow and the periodontal ligament that drove the regeneration.

Epigenetic therapeutics in dental pulp treatment: Hopes, challenges and concerns for the development of next-generation biomaterials

This opinion-led review paper highlights the need for novel translational research in vital-pulp-treatment (VPT), but also discusses the challenges in translating evidence to clinics. Traditional dentistry is expensive, invasive and relies on an outmoded mechanical understanding of dental disease, rather than employing a biological perspective that harnesses cell activity and the regenerative-capacity. Recent research has focussed on developing minimally-invasive biologically-based 'fillings' that preserve the dental pulp; research that is shifting the paradigm from expensive high-technology dentistry, with high failure rates, to smart restorations targeted at biological processes. Current VPTs promote repair by recruiting odontoblast-like cells in a material-dependent process. Therefore, exciting opportunities exist for development of next-generation biomaterials targeted at regenerative processes in the dentin-pulp complex. This article analyses recent research using pharmacological-inhibitors to therapeutically-target histone-deacetylase (HDAC) enzymes in dental-pulp-cells (DPCs) that stimulate pro-regenerative effects with limited loss of viability. Consequently, HDAC-inhibitors have the potential to enhance biomaterial-driven tissue responses at low concentration by influencing the cellular processes with minimal side-effects, providing an opportunity to develop a topically-placed, inexpensive bio-inductive pulp-capping material. Despite positive results, clinical translation of these innovations requires enterprise to counteract regulatory obstacles, dental-industry priorities and to develop strong academic/industry partnerships. The aim of this opinion-led review paper is to discuss the potential role of therapeutically-targeting epigenetic modifications as part of a topical VPT strategy in the treatment of the damaged dental pulp, while considering the next steps, material considerations, challenges and future for the clinical development of epigenetic therapeutics or other 'smart' restorations in VPT.

Adult Mesenchymal Stem Cells from Oral Cavity and Surrounding Areas: Types and Biomedical Applications

Adult mesenchymal stem cells are those obtained from the conformation of dental structures (DMSC), such as deciduous and permanent teeth and other surrounding tissues. Background: The self-renewal and differentiation capacities of these adult stem cells allow for great clinical potential. Because DMSC are cells of ectomesenchymal origin, they reveal a high capacity for complete regeneration of dental pulp, periodontal tissue, and other biomedical applications; their differentiation into other types of cells promotes repair in muscle tissue, cardiac, pancreatic, nervous, bone, cartilage, skin, and corneal tissues, among others, with a high predictability of success. Therefore, stem and progenitor cells, with their exosomes of dental origin and surrounding areas in the oral cavity due to their plasticity, are considered a fundamental pillar in medicine and regenerative dentistry. Tissue engineering (MSCs, scaffolds, and bioactive molecules) sustains and induces its multipotent and immunomodulatory effects. It is of vital importance to guarantee the safety and efficacy of the procedures designed for patients, and for this purpose, more clinical trials are needed to increase the efficacy of several pathologies. Conclusion: From a bioethical and transcendental anthropological point of view, the human person as a unique being facilitates better clinical and personalized therapy, given the higher prevalence of dental and chronic systemic diseases.

Tideglusib-incorporated nanofibrous scaffolds potently induce odontogenic differentiation

Pulp-Dentin regeneration is a key aspect of maintain tooth vitality and enabling good oral-systemic health. This study aimed to investigate a nanofibrous scaffold loaded with a small molecule i.e. Tideglusib to promote odontogenic differentiation. Tideglusib (GSK-3β inhibitor) interaction with GSK-3β was determined using molecular docking and stabilization of β-catenin was examined by confocal microscopy. 3D nanofibrous scaffolds were fabricated through electrospinning and their physicochemical characterizations were performed. Scaffolds were seeded with mesenchymal stem cells or pre-odontoblast cells to determine the cells proliferation and odontogenic differentiation. Our results showed that Tideglusib (TG) binds with GSK-3β at Cys199 residue. Stabilization and nuclear translocation of β-catenin was increased in the odontoblast cells treated with TG. SEM analysis revealed that nanofibers exhibited controlled architectural features that effectively mimicked the natural ECM. UV-Vis spectroscopy demonstrated that TG was incorporated successfully and released in a controlled manner. Both kinds of biomimetic nanofibrous matrices (PCLF-TG100, PCLF-TG1000) significantly stimulated cells proliferation. Furthermore, these scaffolds significantly induced dentinogenic markers (ALP, and DSPP) expression and biomineralization. In contrast to current pulp capping material driving dentin repair, the sophisticated, polymeric scaffold systems with soluble and insoluble spatiotemporal cues described here can direct stem cell differentiation and dentin regeneration. Hence, bioactive small molecule-incorporated nanofibrous scaffold suggests an innovative clinical tool for dentin tissue engineering.

3D Organoids for Regenerative Endodontics

Apical periodontitis is the inflammation and destruction of periradicular tissues, mediated by microbial factors originating from the infected pulp space. This bacteria-mediated inflammatory disease is known to interfere with root development in immature permanent teeth. Current research on interventions in immature teeth has been dedicated to facilitating the continuation of root development as well as regenerating the dentin-pulp complex, but the fundamental knowledge on the cellular interactions and the role of periapical mediators in apical periodontitis in immature roots that govern the disease process and post-treatment healing is limited. The limitations in 2D monolayer cell culture have a substantial role in the existing limitations of understanding cell-to-cell interactions in the pulpal and periapical tissues. Three-dimensional (3D) tissue constructs with two or more different cell populations are a better physiological representation of in vivo environment. These systems allow the high-throughput testing of multi-cell interactions and can be applied to study the interactions between stem cells and immune cells, including the role of mediators/cytokines in simulated environments. Well-designed 3D models are critical for understanding cellular functions and interactions in disease and healing processes for future therapeutic optimization in regenerative endodontics. This narrative review covers the fundamentals of (1) the disease process of apical periodontitis; (2) the influence and challenges of regeneration in immature roots; (3) the introduction of and crosstalk between mesenchymal stem cells and macrophages; (4) 3D cell culture techniques and their applications for studying cellular interactions in the pulpal and periapical tissues; (5) current investigations on cellular interactions in regenerative endodontics; and, lastly, (6) the dental-pulp organoid developed for regenerative endodontics.

Stem cell-derived exosomes for dentin-pulp complex regeneration: a mini-review

This mini-review was conducted to present an overview of the use of exosomes in regenerating the dentin-pulp complex (DPC). The PubMed and Scopus databases were searched for relevant articles published between January 1, 2013 and January 1, 2023. The findings of basic in vitro studies indicated that exosomes enhance the proliferation and migration of mesenchymal cells, as human dental pulp stem cells, via mitogen-activated protein kinases and Wingless-Int signaling pathways. In addition, they possess proangiogenic potential and contribute to neovascularization and capillary tube formation by promoting endothelial cell proliferation and migration of human umbilical vein endothelial cells. Likewise, they regulate the migration and differentiation of Schwann cells, facilitate the conversion of M1 pro-inflammatory macrophages to M2 anti-inflammatory phenotypes, and mediate immune suppression as they promote regulatory T cell conversion. Basic in vivo studies have indicated that exosomes triggered the regeneration of dentin-pulp-like tissue, and exosomes isolated under odontogenic circumstances are particularly strong inducers of tissue regeneration and stem cell differentiation. Exosomes are a promising regenerative tool for DPC in cases of small pulp exposure or for whole-pulp tissue regeneration.

The development of a dental light curable PRFe-loaded hydrogel as a potential scaffold for pulp-dentine complex regeneration: An in vitro study

AIM

The study aimed to develop a bicomponent bioactive hydrogel formed in situ and enriched with an extract of platelet-rich fibrin (PRFe) and to assess its potential for use in pulp-dentine complex tissue engineering via cell homing.

METHODOLOGY

A bicomponent hydrogel based on photo-activated naturally derived polymers, methacrylated chitosan (ChitMA) and methacrylated collagen (ColMA), plus PRFe was fabricated. The optimized formulation of PRFe-loaded bicomponent hydrogel was determined by analysing the mechanical strength, swelling ratio and cell viability simultaneously. The physical, mechanical, rheological and morphological properties of the optimal hydrogel with and without PRFe were determined. Additionally, MTT, phalloidin/DAPI and live/dead assays were carried out to compare the viability, cytoskeletal morphology and migration ability of stem cells from the apical papilla (SCAP) within the developed hydrogels with and without PRFe, respectively. To further investigate the effect of PRFe on the differentiation of encapsulated SCAP, alizarin red S staining, RT-PCR analysis and immunohistochemical detection were performed. Statistical significance was established at p <  .05.

RESULTS

The optimized formulation of PRFe-loaded bicomponent hydrogel can be rapidly photocrosslinked using available dental light curing units. Compared to bicomponent hydrogels without PRFe, the PRFe-loaded hydrogel exhibited greater viscoelasticity and higher cytocompatibility to SCAP. Moreover, it promoted cell proliferation and migration in vitro. It also supported the odontogenic differentiation of SCAP as evidenced by its promotion of biomineralization and upregulating the gene expression for ALP, COL I, DSPP and DMP1 as well as facilitated angiogenesis by enhancing VEGFA gene expression.

CONCLUSIONS

The new PRFe-loaded ChitMA/ColMA hydrogel developed within this study fulfils the criteria of injectability, cytocompatibility, chemoattractivity and bioactivity to promote odontogenic differentiation, which are fundamental requirements for scaffolds used in pulp-dentine complex regeneration via cell-homing approaches.

Biomimetic approaches and materials in restorative and regenerative dentistry: review article

Biomimetics is a branch of science that explores the technical beauty of nature. The concept of biomimetics has been brilliantly applied in famous applications such as the design of the Eiffel Tower that has been inspired from the trabecular structure of bone. In dentistry, the purpose of using biomimetic concepts and protocols is to conserve tooth structure and vitality, increase the longevity of restorative dental treatments, and eliminate future retreatment cycles. Biomimetic dental materials are inherently biocompatible with excellent physico-chemical properties. They have been successfully applied in different dental fields with the advantages of enhanced strength, sealing, regenerative and antibacterial abilities. Moreover, many biomimetic materials were proven to overcome significant limitations of earlier available generation counterpart. Therefore, this review aims to spot the light on some recent developments in the emerging field of biomimetics especially in restorative and regenerative dentistry. Different approaches of restoration, remineralisation and regeneration of teeth are also discussed in this review. In addition, various biomimetic dental restorative materials and tissue engineering materials are discussed.

Effect of chitosan irrigant solutions on the release of bioactive proteins from root dentin

OBJECTIVE

To identify the effect of two chitosan solutions on the release of root dentin matrix proteins and to describe the chemical changes observed following conditioning with chelating agents.

MATERIALS AND METHODS

The release of dentin sialoprotein (DSP), transforming growth factor-beta 1 (TGF-β1), vascular endothelial growth factor (VEGF), and platelet-derived growth factor-BB (PDGF-BB) with different chelating agents, including ethylenediaminetetraacetic acid (EDTA), chitosan solution (CS), and nanoparticulate chitosan (CSnp), was investigated. DSP was quantified using an enzyme-linked immunosorbent assay (ELISA). TGF-β1, VEGF, and PDGF-BB were quantified using a cytokine bead panel (CBA). Raman spectroscopy was performed to identify surface chemical changes. Statistical analysis was performed using Kruskal-Wallis test with Mann-Whitney-Wilcoxon rank-sum test (p < 0.05).

RESULTS

TGF-β1, VEGF, and DSP solubilized in all irrigants tested. CSnp showed the highest concentration of DSP. PDGF-BB did not exceed the detection limits. Raman spectroscopy revealed a decrease in the phosphate and carbonate peaks, representing the chelating effect of EDTA, CS, and CSnp. Additionally, CSnp showed the greatest preservation of the amide I and III content.

CONCLUSION

Proteins can be released from dentin via EDTA, CS, and CSnp conditioning. Raman spectroscopic revealed changes in the inorganic content of the root dentin after chelation. Furthermore, use of CSnp facilitated a preservation of the organic content.

CLINICAL RELEVANCE

Chelation allows the release of proteins, justifying the use of chelating agents in regenerative endodontics. The chitosan-dentin matrix interaction also promotes the protection of the organic content as an additional benefit to its protein releasing effect.

Application of Biocompatible Scaffolds in Stem-Cell-Based Dental Tissue Engineering

Tissue engineering as an important field in regenerative medicine is a promising therapeutic approach to replace or regenerate injured tissues. It consists of three vital steps including the selection of suitable cells, formation of 3d scaffolds, and adding growth factors. Mesenchymal stem cells (MSCs) and embryonic stem cells (ESCs) are mentioned as two main sources for this approach that have been used for the treatment of various types of disorders. However, the main focus of literature in the field of dental tissue engineering is on utilizing MSCs. On the other hand, biocompatible scaffolds play a notable role in this regenerative process which is mentioned to be harmless with acceptable osteoinductivity. Their ability in inhibiting inflammatory responses also makes them powerful tools. Indeed, stem cell functions should be supported by biomaterials acting as scaffolds incorporated with biological signals. Naturally derived polymeric scaffolds and synthetically engineered polymeric/ceramic scaffolds are two main types of scaffolds regarding their materials that are defined further in this review. Various strategies of tissue bioengineering can affect the regeneration of dentin-pulp complex, periodontium regeneration, and whole teeth bioengineering. In this regard, in vivo/ex vivo experimental models have been developed recently in order to perform preclinical studies of dental tissue engineering which make it more transferable to be used for clinic uses. This review summarizes dental tissue engineering through its different components. Also, strategies of tissue bioengineering and experimental models are introduced in order to provide a perspective of the potential roles of dental tissue engineering to be used for clinical aims.

Towards a New Concept of Regenerative Endodontics Based on Mesenchymal Stem Cell-Derived Secretomes Products

The teeth, made up of hard and soft tissues, represent complex functioning structures of the oral cavity, which are frequently affected by processes that cause structural damage that can lead to their loss. Currently, replacement therapy such as endodontics or implants, restore structural defects but do not perform any biological function, such as restoring blood and nerve supplies. In the search for alternatives to regenerate the dental pulp, two alternative regenerative endodontic procedures (REP) have been proposed: (I) cell-free REP (based in revascularization and homing induction to remaining dental pulp stem cells (DPSC) and even stem cells from apical papilla (SCAP) and (II) cell-based REP (with exogenous cell transplantation). Regarding the last topic, we show several limitations with these procedures and therefore, we propose a novel regenerative approach in order to revitalize the pulp and thus restore homeostatic functions to the dentin-pulp complex. Due to their multifactorial biological effects, the use of mesenchymal stem cells (MSC)-derived secretome from non-dental sources could be considered as inducers of DPSC and SCAP to completely regenerate the dental pulp. In partial pulp damage, appropriate stimulate DPSC by MSC-derived secretome could contribute to formation and also to restore the vasculature and nerves of the dental pulp.

Development of Growth Factor Releasing Hyaluronic Acid-Based Hydrogel for Pulp Regeneration: A Preliminary Study

Growth factors play essential roles as signaling molecules in pulp regeneration. We investigated the effect of a hyaluronic acid (HA)-collagen hybrid hydrogel with controlled release of fibroblast growth factor (FGF)-2 and platelet-derived growth factor (PDGF)-BB on human pulp regeneration. The cell interaction and cytotoxicity of the HA-collagen hybrid hydrogel, the release kinetics of each growth factor, and the effects of the released growth factors on pulp cell proliferation were examined. The vitality of pulp cells was maintained. The amounts of FGF-2 and PDGF-BB released over 7 days were 68% and 50%, respectively. Groups with a different concentration of growth factor (FGF-2: 100, 200, 500, and 1000 ng/mL; PDGF-BB: 10, 50, 100, 200, and 500 ng/mL) were experimented on days 1, 3, 5, and 7. Considering FGF-2 concentration, significantly increased pulp cell proliferation was observed on days 1, 3, 5, and 7 in the 100 ng/mL group and on days 3, 5, and 7 in the 200 ng/mL group. In the case of PDGF-BB concentration, significantly increased pulp cell proliferation was observed at all four time points in the 100 ng/mL group and on days 3, 5, and 7 in the 50, 200, and 500 ng/mL groups. This indicates that the optimal concentration of FGF-2 and PDGF-BB for pulp cell proliferation was 100 ng/mL and that the HA-collagen hybrid hydrogel has potential as a controlled release delivery system for FGF-2 and PDGF-BB.

Neural Regeneration in Regenerative Endodontic Treatment: An Overview and Current Trends

Pulpal and periapical diseases are the most common dental diseases. The traditional treatment is root canal therapy, which achieves satisfactory therapeutic outcomes-especially for mature permanent teeth. Apexification, pulpotomy, and pulp revascularization are common techniques used for immature permanent teeth to accelerate the development of the root. However, there are obstacles to achieving functional pulp regeneration. Recently, two methods have been proposed based on tissue engineering: stem cell transplantation, and cell homing. One of the goals of functional pulp regeneration is to achieve innervation. Nerves play a vital role in dentin formation, nutrition, sensation, and defense in the pulp. Successful neural regeneration faces tough challenges in both animal studies and clinical trials. Investigation of the regeneration and repair of the nerves in the pulp has become a serious undertaking. In this review, we summarize the current understanding of the key stem cells, signaling molecules, and biomaterials that could promote neural regeneration as part of pulp regeneration. We also discuss the challenges in preclinical or clinical neural regeneration applications to guide deep research in the future.

Biomimetic Approaches in Clinical Endodontics

In the last few decades, biomimetic concepts have been widely adopted in various biomedical fields, including clinical dentistry. Endodontics is an important sub-branch of dentistry which deals with the different conditions of pulp to prevent tooth loss. Traditionally, common procedures, namely pulp capping, root canal treatment, apexification, and apexigonesis, have been considered for the treatment of different pulp conditions using selected materials. However, clinically to regenerate dental pulp, tissue engineering has been advocated as a feasible approach. Currently, new trends are emerging in terms of regenerative endodontics which have led to the replacement of diseased and non-vital teeth into the functional and healthy dentine-pulp complex. Root- canal therapy is the standard management option when dental pulp is damaged irreversibly. This treatment modality involves soft-tissue removal and then filling that gap through the obturation technique with a synthetic material. The formation of tubular dentine and pulp-like tissue formation occurs when stem cells are transplanted into the root canal with an appropriate scaffold material. To sum up tissue engineering approach includes three components: (1) scaffold, (2) differentiation, growth, and factors, and (3) the recruitment of stem cells within the pulp or from the periapical region. The aim of this paper is to thoroughly review and discuss various pulp-regenerative approaches and materials used in regenerative endodontics which may highlight the current trends and future research prospects in this particular area.

Extraoral Root-End Resection May Promote Pulpal Revascularization in Autotransplanted Mature Teeth-A Retrospective Study

Tooth germ autotransplantation of open apices of the teeth exhibits high pulpal healing rates, whereas that of mature permanent teeth normally causes irreversible pulpal necrosis. Extraoral root-end resection (EORER) during transplantation may promote pulpal revascularization (PRV) in transplanted mature teeth and reduce endodontic treatment requirement. This study compared the primary outcomes of survival rates, PRV, and root resorption and determined relevant confounders in autotransplanted mature and immature teeth. The medical charts of consecutive patients who underwent tooth autotransplantation between January 2017 and March 2021 were evaluated. Teeth with a documented follow-up of at least 1 year were included. During the study period, 59 teeth were transplanted in 44 patients. Overall, 2 teeth were excluded owing to missing data; 57 teeth were analyzed, including 25 mature teeth additionally treated with EORER. After a mean follow-up of 21.2 ± 16.1 months, no significant differences in primary outcomes were detected. Fifty-five teeth remained in situ (96.5%), and radiological signs of root resorption were detected in 9/57 teeth (15.8%). PRV was positive in 54/57 teeth (94.7%). Surgical duration and PRV failure were significantly associated with high incidences of root resorption. Mature teeth autotransplantation with EORER yielded similar results to immature teeth autotransplantation and is a feasible treatment option. Long surgery and failed revascularization increased root resorption rates. More factors should be evaluated in larger trials with longer observation periods.

Expert consensus on regenerative endodontic procedures

Regenerative endodontic procedures (REPs) is a biologic-based treatment modality for immature permanent teeth diagnosed with pulp necrosis. The ultimate objective of REPs is to regenerate the pulp-dentin complex, extend the tooth longevity and restore the normal function. Scientific evidence has demonstrated the efficacy of REPs in promotion of root development through case reports, case series, cohort studies, and randomized controlled studies. However, variations in clinical protocols for REPs exist due to the empirical nature of the original protocols and rapid advancements in the research field of regenerative endodontics. The heterogeneity in protocols may cause confusion among dental practitioners, thus guidelines and considerations of REPs should be explicated. This expert consensus mainly discusses the biological foundation, the available clinical protocols and current status of REPs in treating immature teeth with pulp necrosis, as well as the main complications of this treatment, aiming at refining the clinical management of REPs in accordance with the progress of basic researches and clinical studies, suggesting REPs may become a more consistently evidence-based option in dental treatment.

Betaine promotes osteogenic differentiation in immortalized human dental pulp-derived cells

Objectives

This study aimed to evaluate the effect of betaine (BET) on immortalized human dental pulp stem cell (ihDP) osteogenic differentiation.

Materials and methods

hDPs were immortalized using SV40 T-antigen transfection. Characterization, multilineage differentiation, proliferation, cell cycle, colony-forming unit, and cellular senescence were evaluated (n = 4). The effect of BET on ihDP response was assessed (n = 4). Osteogenic differentiation was detected using ALP, ARS staining, and RT-qPCR (n = 4). To investigate the involvement of calcium signaling, the cells were pretreated with either 8-(NN-diethylamino)octyl-3,4,5-trimethoxybenzoate (TMB-8) or thapsigargin before BET treatment (n = 6).

Results

ihDPs retained similar phenotypic characteristics presented in hDPs but exhibited an increase in cell proliferation and extended culture to passage 25. An increased proportion of cells in S and G2/M phases without senescence was observed in ihDPs. BET (50 mM) treatment significantly increased mineral deposition at 14 days and upregulated ALP, MSX2, BMP2, and RUNX2 expression. TMB-8 pretreatment reduced the effect of BET-induced ihDP osteogenic differentiation, whereas thapsigargin promoted osteogenic differentiation in ihDPs synergistically with BET.

Conclusion

ihDPs showed superior proliferation ability and a longer life span, which could serve as a promising cell for regenerative dentistry. BET promoted odonto/osteogenic differentiation via intracellular calcium regulation.

Tissue Characteristics in Endodontic Regeneration: A Systematic Review

The regenerative endodontic procedure (REP) represents a treatment option for immature necrotic teeth with a periapical lesion. Currently, this therapy has a wide field of pre-clinical and clinical applications, but no standardization exists regarding successful criteria. Thus, by analysis of animal and human studies, the aim of this systematic review was to highlight the main characteristics of the tissue generated by REP. A customized search of PubMed, EMBASE, Scopus, and Web of Science databases from January 2000 to January 2022 was conducted. Seventy-five human and forty-nine animal studies were selected. In humans, the evaluation criteria were clinical 2D and 3D radiographic examinations. Most of the studies identified a successful REP with an asymptomatic tooth, apical lesion healing, and increased root thickness and length. In animals, histological and radiological criteria were considered. Newly formed tissues in the canals were fibrous, cementum, or bone-like tissues along the dentine walls depending on the area of the root. REP assured tooth development and viability. However, further studies are needed to identify procedures to successfully reproduce the physiological structure and function of the dentin–pulp complex.

Cells and material-based strategies for regenerative endodontics

The carious process leads to inflammation of pulp tissue. Current care options include root canal treatment or apexification. These procedures, however, result in the loss of tooth vitality, sensitivity, and healing. Pulp capping and dental pulp regeneration are continually evolving techniques to regenerate pulp tissue, avoiding necrosis and loss of vitality. Many studies have successfully employed stem/progenitor cell populations, revascularization approaches, scaffolds or material-based strategies for pulp regeneration. Here we outline advantages and disadvantages of different methods and techniques which are currently being used in the field of regenerative endodontics. We also summarize recent findings on efficacious peptide-based materials which target the dental niche.

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Bone morphogenetic protein 7 mediates stem cells migration and angiogenesis: therapeutic potential for endogenous pulp regeneration

Pulp loss is accompanied by the functional impairment of defense, sensory, and nutrition supply. The approach based on endogenous stem cells is a potential strategy for pulp regeneration. However, endogenous stem cell sources, exogenous regenerative signals, and neovascularization are major difficulties for pulp regeneration based on endogenous stem cells. Therefore, the purpose of our research is to seek an effective cytokines delivery strategy and bioactive materials to reestablish an ideal regenerative microenvironment for pulp regeneration. In in vitro study, we investigated the effects of Wnt3a, transforming growth factor-beta 1, and bone morphogenetic protein 7 (BMP7) on human dental pulp stem cells (h-DPSCs) and human umbilical vein endothelial cells. 2D and 3D culture systems based on collagen gel, matrigel, and gelatin methacryloyl were fabricated to evaluate the morphology and viability of h-DPSCs. In in vivo study, an ectopic nude mouse model and an in situ beagle dog model were established to investigate the possibility of pulp regeneration by implanting collagen gel loading BMP7. We concluded that BMP7 promoted the migration and odontogenic differentiation of h-DPSCs and vessel formation. Collagen gel maintained the cell adhesion, cell spreading, and cell viability of h-DPSCs in 2D or 3D culture. The transplantation of collagen gel loading BMP7 induced vascularized pulp-like tissue regeneration in vivo. The injectable approach based on collagen gel loading BMP7 might exert promising therapeutic application in endogenous pulp regeneration.

BMP7 as a regenerative signaling molecule mediates stem cell migration and odontoblastic differentiation (a) and as a pro-angiogenic factor promotes revascularization of endothelial cells (b). Collagen gel supports cell adhesion, spreading, and viability (c).

Influencing factors of pulp-dentin complex regeneration and related biological strategies

Regenerative endodontic therapy (RET) utilizing tissue engineering approach can promote the regeneration of pulp-dentin complex to restore pulp vascularization, neuralization, immune function and tubular dentin, therefore the regenerated pulp-dentin complex will have normal function. Multiple factors may significantly affect the efficacy of RET, including stem cells, biosignaling molecules and biomaterial scaffolds. Stem cells derived from dental tissues (such as dental pulp stem cells) exhibit certain advantages in RET. Combined application of multiple signaling molecules and activation of signal transduction pathways such as Wnt/β-catenin and BMP/Smad play pivotal roles in enhancing the potential of stem cell migration, proliferation, odontoblastic differentiation, and nerve and blood vessel regeneration. Biomaterials suitable for RET include naturally-derived materials and artificially synthetic materials. Artificially synthetic materials should imitate natural tissues for biomimetic modification in order to realize the temporal and spatial regulation of pulp-dentin complex regeneration. The realization of pulp-dentin complex regeneration depends on two strategies: stem cell transplantation and stem cell homing. Stem cell homing strategy does not require the isolation and culture of stem cells in vitro, so is better for clinical application. However, in order to achieve the true regeneration of pulp-dentin complex, problems related to improving the success rate of stem cell homing and promoting their proliferation and differentiation need to be solved. This article reviews the influencing factors of pulp-dentin complex regeneration and related biological strategies, and discusses the future research direction of RET, to provide reference for clinical translation and application of RET.

Evaluation of Attitude and Knowledge of Endodontic, Pedodontic and SBARD Residents in Saudi Arabia toward Regenerative Endodontics-A National Survey

Background and Objectives: There are no guidelines on the regenerative endodontic procedures that should be followed in dental treatment. Thus, it is essential to learn the knowledge, attitudes, and opinions about regenerative endodontics among dental practitioners, particularly endodontists, as they are the first providers of this type of dental treatment. Aim: This study aimed to assess the knowledge and attitudes among residents of the Saudi Board of Advanced Restorative Dentistry (SBARD) in Saudi Arabia. Methods & Materials: A questionnaire-based survey was conducted among 128 residents of endodontics, pedodontics, and the SBARD in Saudi Arabia. The questionnaire was distributed to participants using the available electronic measures such as emails and social media. The questionnaire was made by Google Forms, and responses were received directly in the excel sheet in the email. The data were exported as an excel file, coded, and analyzed, and the p-value < 0.05 was set as significant. Results: More than 50% (74 dentists) of the participants reported receiving continuing education in regenerative treatment, with a significant difference found among specialty (p = 0.023). No significant association was found between knowledge, gender, and type of postgraduate study. The vast majority (89.1%) of the participants believed regenerative endodontics should be incorporated into dentistry curricula. About two-thirds (78.2%) of the participants declared their ability to attend future training courses in a regenerative endodontic, whereas 10.9% did not, and 10.9% were unsure. Conclusions: The dental practitioners were enthusiastic and interested in regenerative and stem cell treatment. The results also suggested incorporating regenerative treatment into the dental curriculum and signaled the need for more continued training courses.

Odontogenic Differentiation Induced by TGF-β1 Binding Peptide-Modified Bioglass

Emerging evidence suggests that growth factors are crucial in regenerative endodontic therapy. To achieve the desired effects, the systematic administration of supraphysiologic concentrations of exogenous growth factors is commonly performed, but this is usually associated with high costs, technique, and safety issues. Here, we describe a novel biomaterial that can manipulate endogenous growth factors without the need for adding exogenous growth factors. Transforming growth factor β1 binding peptide (TGFp) was grafted onto the surface of a neutral pH phytic acid-derived bioactive glass (PSC) to synthesize modified bioactive glass (PSC-TGFp). Fourier transform infrared spectroscopy and thermogravimetric analysis results demonstrated that the TGFp was successfully grafted to the surface of the PSC. Scanning electron microscopy and x-ray diffraction showed that PSC-TGFp possessed good in vitro bioactivity. After soaking in simulated body fluid for 24 h, hydroxyapatite formed on the surface of PSC-TGFp. Enzyme-linked immunosorbent assay showed that PSC-TGFp could capture endogenous transforming growth factor β1 from dentin matrix-extracted proteins (DMEP) and release it slowly over 21 d. Cytologic experiments revealed that PSC-TGFp after adsorbing DMEP could enhance the adhesion, migration, viability, and odontogenic differentiation of stem cells from apical papilla. The results highlight that PSC-TGFp may be a promising biomaterial to manipulate endogenous growth factors for regenerative endodontic therapy in the future.

Clinical Potential of Dental Pulp Stem Cells in Pulp Regeneration: Current Endodontic Progress and Future Perspectives

Dental caries is a common disease that not only destroys the rigid structure of the teeth but also causes pulp necrosis in severe cases. Once pulp necrosis has occurred, the most common treatment is to remove the damaged pulp tissue, leading to a loss of tooth vitality and increased tooth fragility. Dental pulp stem cells (DPSCs) isolated from pulp tissue exhibit mesenchymal stem cell-like characteristics and are considered ideal candidates for regenerating damaged dental pulp tissue owing to their multipotency, high proliferation rate, and viability after cryopreservation. Importantly, DPSCs do not elicit an allogeneic immune response because they are non-immunogenic and exhibit potent immunosuppressive properties. Here, we provide an up-to-date review of the clinical applicability and potential of DPSCs, as well as emerging trends in the regeneration of damaged pulp tissue. In addition, we suggest the possibility of using DPSCs as a resource for allogeneic transplantation and provide a perspective for their clinical application in pulp regeneration.

Pro-angiogenic potential of a functionalized hydrogel scaffold as a secretome delivery platform: An innovative strategy for cell homing-based dental pulp tissue engineering

Angiogenesis is a key process that provides a suitable environment for successful tissue engineering and is even more crucial in regenerative endodontic procedures, since the root canal anatomy limits the development of a vascular network supply. Thus, sustainable and accelerated vascularization of tissue-engineered dental pulp constructs remains a major challenge in cell homing approaches. This study aimed to functionalize a chitosan hydrogel scaffold (CS) as a platform loaded with secretomes of stem cells from human exfoliated deciduous teeth (SHEDs) and evaluate its bioactive function and pro-angiogenic properties. Initially, the CS was loaded with SHED secretomes (CS-S), and the release kinetics of several trophic factors were assessed. Proliferation and chemotaxis assays were performed to analyze the effect of functionalized scaffold on stem cells from apical papilla (SCAPs) and the angiogenic potential was analyzed through the Matrigel tube formation assay with co-cultured of human umbilical vein endothelial cells and SCAPs. SHEDs and SCAPs expressed typical levels of mesenchymal stem cell surface markers. CS-S was able to release the trophic factors in a sustained manner, but each factor has its own release kinetics. The CS-S group showed a significantly higher proliferation rate, accelerated the chemotaxis, and higher capacity to form vascular-like structures. CS-S provided a sustained and controlled release of trophic factors, which, in turn, improved proliferation, chemotaxis and all angiogenesis parameters in the co-culture. Thus, the functionalization of chitosan scaffolds loaded with secretomes is a promising platform for cell homing-based tissue engineering.

Biomolecule-Mediated Therapeutics of the Dentin–Pulp Complex: A Systematic Review

The aim of this systematic review was to evaluate the application of potential therapeutic signaling molecules on complete dentin-pulp complex and pulp tissue regeneration in orthotopic and ectopic animal studies. A search strategy was performed according to the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) statement in the MEDLINE/PubMed database. Animal studies evaluating the application of signaling molecules to pulpectomized teeth for pulp tissue or dentin-pulp complex regeneration were included. From 2530 identified records, 18 fulfilled the eligibility criteria and were subjected to detailed qualitative analysis. Among the applied molecules, basic fibroblast growth factor, vascular endothelial growth factor, bone morphogenetic factor-7, nerve growth factor, and platelet-derived growth factor were the most frequently studied. The clinical, radiographical and histological outcome measures included healing of periapical lesions, root development, and apical closure, cellular recolonization of the pulp space, ingrowth of pulp-like connective tissue (vascularization and innervation), mineralized dentin-like tissue formation along the internal dentin walls, and odontoblast-like cells in contact with the internal dentin walls. The results indicate that signaling molecules play an important role in dentin/pulp regeneration. However, further studies are needed to determine a more specific subset combination of molecules to achieve greater efficiency towards the desired tissue engineering applications.

Phosphorylated PAMAM dendrimers: an analog of dentin non-collagenous proteins, enhancing the osteo/odontogenic differentiation of dental pulp stem cells

OBJECTIVES

Polyamidoamine (PAMAM) dendrimers have well-defined structures, with monodispersity and easily modified surface groups, and they have broad applications in biomedicine. In this study, phosphorylated PAMAM (P-PAMAM) dendrimers were synthesized based on the idea of mimicking the phosphorylated proteins of dentin non-collagenous proteins (DNCP). Then, proliferation and osteo/odontogenic differentiation effects of P-PAMAM on dental pulp stem cells (DPSCs) were investigated and were compared with DNCP.

MATERIALS AND METHODS

P-PAMAM was synthesized via the Mannich-type reaction. DNCP were extracted directly from human dentin with ethylenediaminetetraacetic acid (EDTA) solution. Then, the conditioned medium of P-PAMAM and DNCP were prepared respectively and applied to DPSCs. Proliferation of P-PAMAM was investigated with CCK-8, flow cytometry, and EdU test. Osteo/odontogenic differentiation of P-PAMAM was analyzed using alkaline phosphatase activity and staining, RT-PCR, western blot, alizarin red staining, and immunofluorescence staining.

RESULTS

Fourier transform infrared spectroscopy and 1H nuclear magnetic resonance revealed that PAMAM were successfully phosphorylated. Western blot verified that the extracted DNCP contained dentin-related proteins DSPP, OPN, and BMP2. In cell proliferation, there was no apparent difference between P-PAMAM, DNCP, and Control groups (P > 0.05). P-PAMAM and DNCP upregulated related genes and proteins expression (DSPP/DSPP, COL-1/COL-1, ALP/ALP, RUNX2/RUNX2, OSX/OSX, OCN/OCN) and matrix mineralization. Still, the potential was lower than that of DNCP (P < 0.05).

CONCLUSIONS

P-PAMAM dendrimers, as a biomimetic analog of DNCP, promote osteo/odontogenic differentiation of DPSCs without influencing their proliferation at a low concentration.

CLINICAL RELEVANCE

This preliminary study about P-PAMAM dendrimers is expected to provide a more convenient bioactive macromolecular material for the regeneration of the pulp-dentin complex.

Progress and perspectives on cell-free regenerative endodontic therapy

Although teeth with pulpitis/apical periodontitis are saved after successful endodontic therapy, they are devitalized and susceptible to reinfections and fractures. The development of biology-based approaches for dental pulp regeneration or repair is possible today because of recent advances in tissue engineering and biomaterials. Cell-free regenerative endodontic therapy offers a promising strategy for the treatment of necrotic immature permanent teeth in children and adolescents. However, studies are underway to determine whether this procedure can be applied to mature teeth.

Tissue Engineered Neurovascularization Strategies for Craniofacial Tissue Regeneration

Craniofacial tissue injuries, diseases, and defects, including those within bone, dental, and periodontal tissues and salivary glands, impact an estimated 1 billion patients globally. Craniofacial tissue dysfunction significantly reduces quality of life, and successful repair of damaged tissues remains a significant challenge. Blood vessels and nerves are colocalized within craniofacial tissues and act synergistically during tissue regeneration. Therefore, the success of craniofacial regenerative approaches is predicated on successful recruitment, regeneration, or integration of both vascularization and innervation. Tissue engineering strategies have been widely used to encourage vascularization and, more recently, to improve innervation through host tissue recruitment or prevascularization/innervation of engineered tissues. However, current scaffold designs and cell or growth factor delivery approaches often fail to synergistically coordinate both vascularization and innervation to orchestrate successful tissue regeneration. Additionally, tissue engineering approaches are typically investigated separately for vascularization and innervation. Since both tissues act in concert to improve craniofacial tissue regeneration outcomes, a revised approach for development of engineered materials is required. This review aims to provide an overview of neurovascularization in craniofacial tissues and strategies to target either process thus far. Finally, key design principles are described for engineering approaches that will support both vascularization and innervation for successful craniofacial tissue regeneration.

Regenerative Endodontic Procedures for the Treatment of Necrotic Mature Teeth: A Preliminary Randomised Clinical Trial

AIM

This preliminary randomised, prospective, controlled trial aimed to compare the clinical and radiographic outcomes of two regenerative endodontic procedures (REPs), revitalisation and a platelet-rich fibrin (PRF)-based technique, in the treatment of mature permanent teeth with necrotic pulps.

METHODOLOGY

The trial has been reported according to the Preferred Reporting Items for Randomised Trials in Endodontics 2020 guidelines. The study protocol was registered at the clinical trial registry (ClinicalTrials.gov) with identifier number NCT04158232. Twenty patients with mature necrotic anterior teeth with large periapical lesions were randomly allocated into two groups (n=10): group I, treated with revitalisation with the blood clot (BC) technique, and Group II, treated with a PRF-based technique. The follow-up was for 12 months. Periradicular healing was assessed using standardised radiographs taken at baseline, and at 6 and 12 months after treatment. An electric pulp tester was used to assess whether pulp sensibility had been regained during the follow-up period. Statistical analysis was conducted using Mann-Whitney test and Wilcoxon test for non-parametric data. For parametric data, repeated measures analysis of variance was used. The significance level was set at P≤0.05.

RESULTS

There was a significant increase in periradicular healing in both groups at 6 and 12 months, compared to that at baseline, with no significant difference between the studied groups after 12 months (P=0.143). There was a significant difference between the tooth sensibility readings at baseline, 6-month, and 12-month follow-up timepoints (P<0.001).

CONCLUSIONS

The findings of this preliminary trial indicate the potential for using REPs, such as revitalisation or PRF-based techniques, as treatment options for mature teeth with necrotic pulps. A higher level of evidence obtained through adequately powered clinical trials and longer follow-up periods are required to conclusively validate the different outcomes of REPs.

Hypes and Hopes of Stem Cell Therapies in Dentistry: a Review

One of the most exciting advances in life science research is the development of 3D cell culture systems to obtain complex structures called organoids and spheroids. These 3D cultures closely mimic in vivo conditions, where cells can grow and interact with their surroundings. This allows us to better study the spatio-temporal dynamics of organogenesis and organ function. Furthermore, physiologically relevant organoids cultures can be used for basic research, medical research, and drug discovery. Although most of the research thus far focuses on the development of heart, liver, kidney, and brain organoids, to name a few, most recently, these structures were obtained using dental stem cells to study in vitro tooth regeneration. This review aims to present the most up-to-date research showing how dental stem cells can be grown on specific biomaterials to induce their differentiation in 3D. The possibility of combining engineering and biology principles to replicate and/or increase tissue function has been an emerging and exciting field in medicine. The use of this methodology in dentistry has already yielded many interesting results paving the way for the improvement of dental care and successful therapies.

Delivery of affordable and scalable encapsulated allogenic/autologous mesenchymal stem cells in coagulated platelet poor plasma for dental pulp regeneration

The main goal of regenerative endodontics procedures (REPs) is to revitalize teeth by the regeneration of healthy dental pulp. In this study, we evaluated the potential of combining a natural and accessible biomaterial based on Platelet Poor Plasma (PPP) as a support for dental pulp stem cells (DPSC) and umbilical cord mesenchymal stem cells (UC-MSC). A comparison study between the two cell sources revealed compatibility with the PPP based scaffold with differences noted in the proliferation and angiogenic properties in vitro. Additionally, the release of growth factors including VEGF, HGF and DMP-1, was detected in the media of cultured PPP and was enhanced by the presence of the encapsulated MSCs. Dentin-Discs from human molars were filled with PPP alone or with MSCs and implanted subcutaneously for 4 weeks in mice. Histological analysis of the MSC-PPP implants revealed a newly formed dentin-like structure evidenced by the expression of Dentin sialophosphoprotein (DSPP). Finally, DPSC induced more vessel formation around the dental discs. This study provides evidence of a cost-effective, xenofree scaffold that is compatible with either autologous or allogenic strategy for dental pulp regeneration. This attempt if successfully implemented, could make REPs treatment widely accessible, contributing in improving global health conditions.