Cell-Based Regenerative Endodontics for Treatment of Periapical Lesions: A Randomized, Controlled Phase I/II Clinical Trial

Alginate-hydroxyapatite scaffolds: A comprehensive characterization study

Introduction

Alginate has garnered significant attention in regenerative dentistry for its biocompatibility, mechanical strength, and controlled biodegradability. The incorporation of hydroxyapatite enhances its ability to mimic the dentin extracellular matrix, promoting cellular adhesion, proliferation, and mineralization. This study aims to comprehensively assess the structural, chemical, and biological properties of Alg-HA scaffolds to evaluate their potential for dentin regeneration.

Methods

Alginate-hydroxyapatite (Alg-HA) scaffolds were synthesized by dissolving sodium alginate (2 % w/v) in distilled water, followed by the incorporation of hydroxyapatite (HA) synthesized via chemical precipitation using calcium nitrate tetrahydrate and ammonium phosphate. The composite solution was homogenized through stirring and ultrasonication before being freeze-dried to fabricate porous scaffolds. Characterization was performed using X-ray Diffraction (XRD) to confirm crystallinity, Fourier Transform Infrared Spectroscopy (FTIR) to verify functional group interactions, and Scanning Electron Microscopy (SEM) with Energy Dispersive X-ray Analysis (EDAX) to analyze morphology and elemental composition. In vitro degradation studies were conducted in simulated body fluid (SBF) to assess scaffold stability by measuring mass loss over time, with additional pH monitoring and SEM analysis for morphological changes. Hemocompatibility was evaluated through hemolysis assays, comparing scaffold-incubated blood samples to positive and negative controls.

Results

XRD analysis confirmed the successful incorporation of HA within the alginate matrix, highlighting characteristic HA peaks and alginate's amorphous nature. FTIR analysis validated the composite formation through phosphate-carboxylate interactions. SEM imaging revealed a porous, interconnected structure with embedded HA particles, facilitating cell attachment and proliferation. EDAX confirmed the presence of calcium, phosphorus, and oxygen as primary constituents. In vitro degradation studies showed controlled degradation, with 80 % mass loss by day 3, indicating the composite's suitability for gradual tissue replacement. Hemocompatibility tests revealed minimal hemolysis (<2 %), confirming the composite's excellent blood compatibility.

Conclusion

The findings emphasize the potential of Alg-HA scaffolds for dentin regeneration. Their porous architecture, combined with embedded HA, enhances mechanical stability while providing essential biochemical cues for cell proliferation and mineralization. The demonstrated hemocompatibility ensures safe application in direct blood contact, reducing immune responses and promoting tissue integration. Compared to previous studies, this research offers a more in-depth understanding of the relationship between porosity, mineralization, and cellular behavior. Alginate-hydroxyapatite scaffolds exhibit excellent structural, chemical, and biological properties, making them promising candidates for regenerative dentistry. With excellent degradation, hemocompatibility, and ability to support cellular functions, these scaffolds hold significant potential for clinical applications, with further optimization paving the way for broader medical adoption.

Boosting the angiogenesis potential of self-assembled mesenchymal stem cell spheroids by size mediated physiological hypoxia for vascularized pulp regeneration

Hypoxia is a pivotal factor in enhancing the vascularization potential of both two-dimensional (2D) cultured cells and three-dimensional (3D) cellular spheroids. Nevertheless, spheroids that closely mimic the in vivo microenvironment often experience excessive hypoxia, leading to the necrotic core and the release of toxic byproducts, ultimately impeding the regenerative process. To balance cell vitality and pro-angiogenic properties of cellular spheroids, this study investigates size-dependent hypoxia in stem cell spheroids utilizing an oxygen transfer finite element model. Subsequently, we develop 3D cultured stem cells from human exfoliated deciduous teeth (SHED) spheroids with regulated size-dependent hypoxia. Comprehensive assessments indicate that SHED spheroids, inoculated at a density of 50,000 cells, display moderate physiological hypoxia, which optimizes their pro-angiogenic potential, fusion capacity, and reattachment ability. Compared with SHED sheets, SHED spheroids enhance vascularized pulp regeneration more effectively with a tightly connected odontoblastic-like layer. Moreover, high-throughput transcriptome sequencing and RT-qPCR analysis further confirm the spheroids' ability to promote angiogenesis and odontogenic differentiation. This study not only introduces a practical and effective approach for regulating size-dependent hypoxia in cellular spheroids, and simultaneously enhancing cell vitality and angiogenic potential, but also paves the way for the clinical application of SHED spheroids in regenerative dental pulp therapies. STATEMENT OF SIGNIFICANCE: The core of three-dimensionally cultured cellular spheroids often experiences hypoxia, and maintaining a balance between the activity and functionality of long-term cultured spheroids in the inevitably hypoxic microenvironment remains a significant challenge. This study introduces a method to optimize the hypoxic conditions of SHED spheroids by employing a reaction-diffusion model, which modulates internal hypoxia to balance cellular viability and angiogenic potential. Compared to two-dimensional cell sheets, the optimized SHED spheroids with high cell vitality, angiogenesis potential, tissue integration and reattatchment ability show superior efficacy in promoting the formation of vascularized pulp-like tissue. This work offers valuable insights into the role of hypoxia in stem cell spheroids functionality and provides a foundation for further research into the optimization of stem cell-based therapies for multiple clinical applications.

Endodontic Regeneration Therapy: Current Strategies and Tissue Engineering Solutions

With increasing life expectancy and an aging population, the demand for dental treatments that preserve natural teeth has grown significantly. Among these treatments, endodontic therapies for pulpitis and apical periodontitis play a vital role, not only in keeping occlusal function, but also in preventing the exacerbation of systemic diseases. Both pulpitis and apical periodontitis are primarily caused by infections of the oral pathobiont within the root canal, leading to inflammation and destruction of the pulp, apical periodontal tissue, and bone. Standard root canal therapy aims to remove the infection source and facilitate natural tissue healing through the body's regenerative capacity. However, challenges remain, including limited tooth functionality after complete pulp removal in pulpitis and insufficient recovery of the large bone defect in apical periodontitis. To address these limitations, endodontic regenerative therapies have emerged as promising alternatives. Pulp regeneration therapy seeks to restore the functionality of dental pulp, while bone regeneration therapy aims to repair and regenerate large bone defects affected by apical periodontal tissue.

Angiogenic and neurogenic potential of dental-derived stem cells for functional pulp regeneration: A narrative review

BACKGROUND

Dental pulp tissue engineering is expected to become an ideal treatment for irreversible pulpitis and apical periodontitis. However, angiogenesis and neurogenesis for functional pulp regeneration have not yet met the standard for large-scale clinical application, and need further research.

OBJECTIVE

This review focused on the potential mechanisms of angiogenesis and neurogenesis in pulp regeneration, including stem cell types, upstream and downstream regulatory molecules and cascade signalling pathways, thereby providing a theoretical basis and inspiring new ideas to improve the effectiveness of dental pulp tissue engineering.

METHODS

An electronic literature search was carried out using the keywords of 'pulp regeneration', 'stem cell transplantation', 'dental pulp stem cells', 'angiogenesis' and 'neurogenesis'. The resulting literature was screened and reviewed.

RESULTS

Stem cells used in dental pulp tissue engineering can be classified as dental-derived and non-dental-derived stem cells, amongst which dental pulp stem cells (DPSC) have achieved promising results in animal experiments and clinical trials. Multiple molecules and signalling pathways are involved in the process of DPSC-mediated angiogenic and neurogenetic regeneration. In order to promote angiogenesis and neurogenesis in pulp regeneration, feasible measures include the addition of growth factors, the modulation of transcription factors and signalling pathways, the use of extracellular vesicles and the modification of bioscaffold materials.

CONCLUSION

Dental pulp tissue engineering has had breakthroughs in preclinical and clinical studies in vivo. Overcoming difficulties in pulpal angiogenesis and neurogenesis, and achieving functional pulp regeneration will lead to a significant impact in endodontics.

Machine learning models for prognosis prediction in regenerative endodontic procedures

BACKGROUND

This study aimed to establish and validate machine learning (ML) models to predict the prognosis of regenerative endodontic procedures (REPs) clinically, assisting clinicians in decision-making and avoiding treatment failure.

METHODS

A total of 198 patients with 268 teeth were included for radiographic examination and measurement. Five Machine Learning (ML) models, including Random forest (RF), gradient boosting machine (GBM), extreme gradient boosting (XGB), Logistic regression (logR) and support vector machine (SVM) are implemented for the prediction on two datasets of follow-up periods of 1-year and 2-year, respectively. Using a stratified five folds of cross-validation method, each dataset is randomly divided into a training set and test set in a ratio of 8 : 2. Correlation analysis and importance ranking were performed for feature extraction. Seven performance metrics including area under curve (AUC), accuracy, F1-score, sensitivity, specificity, positive predictive value (PPV) and negative predictive value (NPV) were calculated to compare the predictive performance.

RESULTS

The RF (Accuracy = 0.91, AUC = 0.94; Accuracy = 0.84, AUC = 0.86) and GBM (Accuracy = 0.91, AUC = 0.93; Accuracy = 0.84, AUC = 0.85) had the best and similar performance simultaneously in the prediction of 1-year follow-up period and 2-year follow-up period, respectively. The variables applied to predict the primary outcome in REPs were ranked accordingly to their values of feature importance, including age, sex, etiology, the number of root canals, trauma type, swelling or sinus tract, periapical lesion size, root development stage, pre-operative root resorption, medicaments, scaffold, second REPs, previous root canal filling.

CONCLUSIONS

RF and GBM models outperformed XGB, logR, SVM models on the overall performance on our datasets, exhibiting the potential capability to predict the prognosis of REPs. The ranking of feature importance contributes to establishing the scoring system for prognosis prediction in REPs, assisting clinicians in decision-making.

Clinical-grade extracellular vesicles derived from umbilical cord mesenchymal stromal cells: preclinical development and first-in-human intra-articular validation as therapeutics for knee osteoarthritis

Osteoarthritis (OA) is a joint disease characterized by articular cartilage degradation. Persistent low-grade inflammation defines OA pathogenesis, with crucial involvement of pro-inflammatory M1-like macrophages. While mesenchymal stromal cells (MSC) and their small extracellular vesicles (sEV) hold promise for OA treatment, achieving consistent clinical-grade sEV products remains a significant challenge. This study aims to develop fully characterized, reproducible, clinical-grade batches of sEV derived from umbilical cord (UC)-MSC for the treatment of OA while assessing its efficacy and safety. Initially, a standardized, research-grade manufacturing protocol was established to ensure consistent sEV production. UC-MSC-sEV characterization under non-cGMP conditions showed consistent miRNA and protein profiles, suggesting their potential for standardized manufacturing. In vitro studies evaluated the efficacy, safety, and potency of sEV; animal studies confirmed their effectiveness and safety. In vitro, UC-MSC-sEV polarized macrophages to an anti-inflammatory M2b-like phenotype, through STAT1 modulation, indicating their potential to create an anti-inflammatory environment in the affected joints. In silico studies confirmed sEV's immunosuppressive signature through miRNA and proteome analysis. In an OA mouse model, sEV injected intra-articularly (IA) induced hyaline cartilage regeneration, validated by histological and μCT analyses. The unique detection of sEV signals within the knee joint over time highlights its safety profile by confirming the retention of sEV in the joint. The product development of UC-MSC-sEV involved refining, standardizing, and validating processes in compliance with GMP standards. The initial assessment of the safety of the clinical-grade product via IA administration in a first-in-human study showed no adverse effects after a 12 month follow-up period. These results support the progress of this sEV-based therapy in an early-phase clinical trial, the details of which are presented and discussed in this work. This study provides data on using UC-MSC-sEV as local therapy for OA, highlighting their regenerative and anti-inflammatory properties and safety in preclinical and a proof-of-principle clinical application.

Approaches to regenerative endodontic therapy in necrotic human teeth with complete root formation: a systematic review

INTRODUCTION

Regenerative endodontic procedures (REPs) aim to replace damaged dental structures and regenerate the dentin-pulp complex. Initially focused on teeth with incomplete root formation, recent research shows promise for necrotic teeth with complete root formation.

METHODOLOGY

This review, following PRISMA guidelines and registered in PROSPERO, included clinical studies on regenerative endodontic therapy in necrotic human teeth with complete root formation. Searches in PubMed, Web of Science, Embase, and Cochrane Library identified 10 studies meeting the criteria.

RESULTS

The studies showed variable regenerative endodontic protocols and materials, with success rates ranging from 60 to 100%. Most studies reported favorable outcomes, such as symptom resolution and bone healing.

DISCUSSION

Regenerative endodontic therapy for necrotic teeth with complete root formation shows high success rates, but the variability in protocols calls for standardized guidelines and further high-quality trials.

CONCLUSION

Regenerative endodontic therapy is a promising alternative to conventional treatments for necrotic teeth with complete root formation, with demonstrated potential for restoring pulp vitality.Future research should optimize protocols and materials for consistent success.

Regenerative Endodontic Procedures With Minced Pulp Tissue Graft in Mature Permanent Teeth: A Clinical Study

INTRODUCTION

Regenerative endodontic procedures (REPs) using cell-based approaches have emerged as novel treatment modalities. This clinical study aimed to present the outcomes and explore factors influencing REPs with minced pulp tissue (MP) grafts in a mature tooth.

METHODS

Healthy patients requiring non-surgical root canal treatment were enrolled. MP obtained from the third molar was grafted into the instrumented, disinfected, and blood-filled root canal. After treatment, patients were evaluated clinically and radiographically.

RESULTS

Follow-ups for 6 cases (male patients aged 20-27) ranged from 19 to 42 months. Radiographically, all the teeth showed favorable outcomes. Among the 6 teeth, 2 showed neither intracanal calcification nor recovery in sensibility tests, and one had no intracanal calcification with an inapplicable sensibility test evaluation. In 2 teeth, intracanal calcification was observed in the apical third; however, there was no recovery in the sensibility tests. One tooth exhibited intracanal calcification in the apical third and showed recovery in the sensibility tests. Considering these outcomes and clinical variables, the size of the apical foramen and the composition of the transplanted pulp tissue were identified as tentative influencing factors.

CONCLUSIONS

This exploratory clinical study on simplified cell-based REPs using autologous MP grafts for pulp/dentin regeneration in adult teeth not only enhances our understanding of REPs but also suggests its potential as an alternative treatment option to conventional endodontic treatment.

Feasibility and Outcomes of Cell-based Regenerative Endodontic Therapy in Postautogenous Transplantation of a Mature Tooth: A Case Report

Autogenous tooth transplantation (ATT) offers advantages; however, success rates depend on factors like socket formation, donor tooth manipulation, and endodontic treatment. Root canal treatment in a mature post-ATT tooth remains challenging. Cell-based regenerative endodontic therapy (RET) shows promise for regenerating the pulp-dentin complex in mature teeth. However, its application in a post-ATT tooth is unexplored. This case report demonstrates the feasibility and outcomes of cell-based RET in a post-ATT tooth. A 37-year-old male underwent ATT for a missing maxillary left first molar. The maxillary right third molar served as the donor tooth and transplanted with surgical guides. Root canal treatment began two weeks after ATT, confirming no detectable residual bacteria and fungi after 11 weeks. Dental pulp stem cells isolated from the maxillary left third molar were transplanted into the root canal 17 weeks after ATT. The ATT tooth responded positively to the electric pulp test after 1 week. Most of the periodontal ligament of the donor tooth was absent, and the ATT tooth initially showed ankylosis-like signs but regained normal mobility after 28 weeks after RET. Cone-beam computed tomography imaging showed successful outcomes with the presence of the periodontal ligament space and lamina dura, and without root resorption and ankylosis after 52 weeks. Magnetic resonance imaging revealed signal intensity of the regenerated tissue comparable to normal pulp after 60 weeks. This case report suggests the effectiveness of dental pulp stem cells in regenerating dental pulp and periodontal ligament, potentially preventing root resorption and ankylosis in the post-ATT tooth.

The Effect of Exosomes Derived from Human Umbilical Cord Mesenchymal Stromal/Stem Cells on the Regeneration of Human Pulpectomized Tooth: A Case Report

The dental pulp is essential for tooth health and sensory function. However, conventional treatments for infected or necrotic pulp, such as root canal therapy, frequently result in tooth loss and increased fracture risk. Regenerative endodontic procedures (REPs) aim to regenerate pulp tissue while preserving tooth vitality. Exosomes from human umbilical cord mesenchymal stromal/stem cells (hUCMSCs) demonstrated potential for tissue regeneration. In this case report, the potential of hUCMSC-derived exosomes for regenerating the dental pulp of a pulpectomized tooth was investigated. The patient, a 40-year-old man, was presented with irreversible pulpitis in the mandibular second premolar. The patient underwent a pulpectomy, followed by the application of a chitosan and hUCMSC-derived exosome mixture into the root canal. This project was conceived and executed as a joint project in Bushehr (Iran), Shiraz (Iran), and Aktobe (Kazakhstan) from 2022 to 2024. Exosomes were isolated and characterized using scanning electron microscopy (SEM) and transmission electron microscopy (TEM). Clinical evaluations, including visual inspection, palpation, pulp vitality tests, radiography, and cone beam computed tomography (CBCT) imaging, were conducted over 24 weeks post-treatment. The SEM and TEM images confirmed the effective isolation and characterization of exosomes. Clinical follow-ups showed no signs of infection, swelling, or tenderness around the treated tooth. Radiographic assessments indicated periapical radiolucency and periodontal ligament widening, suggesting active healing. Despite these radiographic changes, the absence of clinical symptoms indicated successful tissue regeneration and integration. This case report demonstrated the potential of hUCMSC-derived exosomes for dental pulp regeneration, with promising results in maintaining tooth vitality and promoting healing.

Regenerative Treatment of Mature Teeth with Pulp Necrosis and Apical Periodontitis Using Biodentine Compared with MTA: Randomized Controlled Clinical Trial

OBJECTIVE

The purpose of this randomized, controlled study was to evaluate the effectiveness of Biodentine compared with MTA used as a pulp space barrier in healing periapical lesions and regaining pulp sensitivity after regenerative treatment in mature single-canal permanent teeth with pulp necrosis and apical periodontitis.

METHODS

The study involved 36 patients with mature teeth with necrotic pulp and apical periodontitis. The patient underwent a regenerative treatment that utilized the blood clot technique. Teeth were randomly allocated to either the intervention, Biodentine, group (n=18) or the control, MTA, group (n=18). The healing of periapical lesions and tooth sensibility were evaluated throughout follow-up visits for up to 18 months.

RESULTS

The study analyzed 31 patients; two patients within the biodentine group and three in the MTA group were lost to follow-up. After 18 months, both groups showed effective healing of periradicular lesions; 21 out of 31 patients (67.7%) were healed, ten patients (32.3%) were healing, and no failure cases occurred. There were no significant differences between the groups (p=1.00). More than 70% (22 out of 31 patients) regained their sensibility in their teeth, and the groups had no statistically significant difference (p=0.703).

CONCLUSION

Regenerative treatment using blood clots with either MTA or Biodentine effectively resolved periapical lesions and regained the sensibility of mature teeth.

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.

The Therapeutic Use of Dental Mesenchymal Stem Cells in Human Clinical Trials

Mesenchymal stem cells (MSCs), characterized by their undifferentiated and multipotent nature, can be derived from various sources, including bone marrow, adipose, and dental tissues. Among these, dental MSCs (DSCs) exhibit universal MSC characteristics and are attracting considerable attention for regenerating oral and craniofacial tissues. This review provides a contemporary overview of recently published clinical studies using DSCs for various orodental and maxillofacial regenerative applications, including bone, periodontal, and endodontic regeneration. It also explores the utilization of DSCs in treating systemic conditions, exemplified by their application in managing conditions such as COVID-19 and osteoarthritis. The available evidence underscores the potential of DSCs and their secretome as efficacious tools in regenerative medicine for both dental and nondental clinical applications, supporting the continued promise of stem cell-based therapies. It is nevertheless evident that there are a number of important challenges that restrict the widespread utilization of DSCs, namely, difficulty in standardizing autologous preparations, insufficient cell surface marker characterization, high production costs, and regulatory compliance requirements. Further, the unique requirements of dental applications, especially complex structures such as the periodontium, where temporospatial control over the healing process is required, necessitate the combination of stem cells with appropriate scaffolds according to the principles of tissue engineering. There is currently insufficient evidence to support the clinical translation of DSCs into clinical practice, and phase 3 clinical trials with standardized protocols for cell sourcing, propagation, dosing, and delivery are required to move the field forward. In summary, this review provides a contemporary overview of the evolving landscape of stem cell therapy, offering insights into the latest developments and trends as well as the challenges that need to be addressed for the widespread application of DSC-based cell therapies.

Top 100 most-cited scientific articles in regenerative endodontics 2019-2023: A bibliometric analysis

BACKGROUND

Bibliometric analysis is a critical indicator of the influence and relevance of scientific papers, whilst also highlighting key contributors and gaps in knowledge in a scientific field.

OBJECTIVES

To update and analyse the 100 most-cited papers in regenerative endodontics from 2019 to 2023.

METHODS

A search of the most-cited recent papers focusing on regenerative endodontics using journals included in the category, 'Dentistry, Oral Surgery & Medicine', in the Clarivate Web of Science database from 2019 to 2023 was performed. Three researchers conducted the study selection and data extraction. Data extraction included publication title and year, authors, number and mean number of citations, institution, country and continent, study design, journal title, keywords and research topic. Citation counts were also collected in Google Scholar and Scopus databases. Graphical bibliometric networks were created using VOSviewer software.

RESULTS

The number of citations of the 100 most-cited articles ranged from 6 to 85. Most were published in 2020 (n = 48), principally in the Journal of Endodontics (47%), followed by International Endodontic Journal (13%), Journal of Dental Research (6%) and Dental Materials (6%). Laboratory study was the most common study design amongst the included papers (n = 47), followed by narrative reviews (n = 17) and observational studies (n = 16). The most frequent first author on the top three most-cited papers was Hacer Aksel, whilst Adham A. Azim (n = 6; 89 citations) contributed most to the top 100 articles. The institution from which most articles originated was the University of Hong Kong (China) (n = 5; 81 citations), whereas the corresponding authors were predominantly from the United States of America (USA) (n = 31; 560 citations). The VOSviewer map of co-authorship demonstrated research collaborative clusters. 'Regenerative endodontics' and 'stem-cells' were the most employed keywords (37 and 36 occurrences respectively).

DISCUSSION

The current study was designed not only to showcase the most influential papers in regenerative endodontics since 2019 but also to provide a better understanding of global research in this area over the last five years.

CONCLUSIONS

This bibliometric analysis highlighted papers, authors, institutions and keywords in regenerative endodontics. The 100 most-cited papers primarily consisted of laboratory studies published in the USA, focusing on evaluating biomaterials and scaffold design strategies in contact with stem cells. Clinical studies and systematic reviews representing higher levels of scientific evidence are currently not the most influential in the regenerative endodontic field.

Survival advantage of native and engineered T cells is acquired by mitochondrial transfer from mesenchymal stem cells

BACKGROUND

Apoptosis, a form of programmed cell death, is critical for the development and homeostasis of the immune system. Chimeric antigen receptor T (CAR-T) cell therapy, approved for hematologic cancers, retains several limitations and challenges associated with ex vivo manipulation, including CAR T-cell susceptibility to apoptosis. Therefore, strategies to improve T-cell survival and persistence are required. Mesenchymal stem/stromal cells (MSCs) exhibit immunoregulatory and tissue-restoring potential. We have previously shown that the transfer of umbilical cord MSC (UC-MSC)-derived mitochondrial (MitoT) prompts the genetic reprogramming of CD3+ T cells towards a Treg cell lineage. The potency of T cells plays an important role in effective immunotherapy, underscoring the need for improving their metabolic fitness. In the present work, we evaluate the effect of MitoT on apoptotis of native T lymphocytes and engineered CAR-T cells.

METHODS

We used a cell-free approach using artificial MitoT (Mitoception) of UC-MSC derived MT to peripheral blood mononuclear cells (PBMCs) followed by RNA-seq analysis of CD3+ MitoTpos and MitoTneg sorted cells. Target cell apoptosis was induced with Staurosporine (STS), and cell viability was evaluated with Annexin V/7AAD and TUNEL assays. Changes in apoptotic regulators were assessed by flow cytometry, western blot, and qRT-PCR. The effect of MitoT on 19BBz CAR T-cell apoptosis in response to electroporation with a non-viral transposon-based vector was assessed with Annexin V/7AAD.

RESULTS

Gene expression related to apoptosis, cell death and/or responses to different stimuli was modified in CD3+ T cells after Mitoception. CD3+MitoTpos cells were resistant to STS-induced apoptosis compared to MitoTneg cells, showing a decreased percentage in apoptotic T cells as well as in TUNEL+ cells. Additionally, MitoT prevented the STS-induced collapse of the mitochondrial membrane potential (MMP) levels, decreased caspase-3 cleavage, increased BCL2 transcript levels and BCL-2-related BARD1 expression in FACS-sorted CD3+ T cells. Furthermore, UC-MSC-derived MitoT reduced both early and late apoptosis in CAR-T cells following electroporation, and exhibited an increasing trend in cytotoxic activity levels.

CONCLUSIONS

Artificial MitoT prevents STS-induced apoptosis of human CD3+ T cells by interfering with the caspase pathway. Furthermore, we observed that MitoT confers protection to apoptosis induced by electroporation in MitoTpos CAR T-engineered cells, potentially improving their metabolic fitness and resistance to environmental stress. These results widen the physiological perspective of organelle-based therapies in immune conditions while offering potential avenues to enhance CAR-T treatment outcomes where their viability is compromised.

Web-Based Survey on Regenerative Endodontic Practices among Members of the American Association of Endodontists

INTRODUCTION

The American Association of Endodontics (AAE) Regenerative Endodontics Committee reports here the web-based survey data of regenerative endodontic procedures performed by the AAE members from 2008 to 2019.

METHODS

The web-based survey consisted of 2 questionnaires, a revascularization and a follow-up, including clinical and radiographic data at 3, 6, 12 or >12 months after treatment. Data from demographics, etiology, clinical protocols, radiographic, and clinical outcome as perceived by the clinicians were recorded. From 927 entries, 184 full cases were submitted and 126 were suitable for radiographic analysis. The data were divided into cases with 6-12 months and cases with >12 months recall time. Descriptive statistics and univariate analyses were performed.

RESULTS

Predominantly patients were male (63%), average 10 years-old with anterior teeth (77.2%) due to trauma (69.6%). A wide variation in regenerative endodontic procedures protocols was reported by the AAE members. The most common clinical protocols used minimal instrumentation (75.5%), 2.5% or higher concentrations of sodium hypochlorite (83.7%), and antibiotic paste as intracanal medication (58.7%). The majority reported blood clot formation (56%) and most common coronal capping material was white mineral trioxide aggregates (50.5%). Increases in radiographic root length, and radiographic root area were proportional to the time lapsed after treatment. Overall, case outcomes were categorized by clinicians as successful (54.3%), uncertain (23.9%), and unsuccessful (3.8%).

CONCLUSIONS

This web-based survey provides a valuable perspective on case selection, clinical protocols, and perceived outcomes for regenerative endodontic procedures and supports the need for future higher level evidence studies.

Orthodontic movement after regenerative endodontic procedure in mature permanent tooth associated with dens invaginatus: a case report with 4-year follow-up

BACKGROUND

Regenerative endodontic procedures (REPs) are innovative treatments aimed at restoring damaged dental structures. However, the effect of orthodontic movement on REP-treated teeth is not well understood and may have significant long-term consequences. This study aimed to evaluate the impact of orthodontic movement on a mature permanent tooth associated with dens invaginatus that has undergone a regenerative endodontic procedure (REP).

CASE PRESENTATION

This report describes the case of a 13-year-old healthy male who presented with pulp necrosis and a chronic apical abscess (tooth number 2.2). Following REP according to the American Association of Endodontists' guidelines, the patient began non-extraction orthodontic treatment with fixed appliances after a 9-month healing period, which lasted 17 months in the upper arch. Subsequent follow-ups at 24, 36 and 48 months post-REP revealed an asymptomatic state with minimal cervical discoloration and diminished cold sensitivity. Radiographic analyses revealed periapical healing, mild apical remodeling on tooth 2.2, and moderate apical remodeling on other maxillary incisors. The treated tooth displayed a positive response to both REP and orthodontic treatment, yet further research is required to determine the long-term effects of orthodontics on REP-treated teeth.

CONCLUSION

Orthodontic movement following REPs in mature permanent teeth is feasible and do not seem to prone teeth to orthodontic tooth resorption. Our experience indicates that a 9-month healing period allows successful orthodontic outcomes following REPs. Nonetheless, the predictability of outcomes and the ideal healing period before orthodontic movement is initiated remain to be established.

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.

Regenerative application of oral and maxillofacial 3D organoids based on dental pulp stem cell

Dental pulp stem cells (DPSCs) originate from the neural crest and the present mesenchymal phenotype showed self-renewal capabilities and can differentiate into at least three lineages. DPSCs are easily isolated with minimal harm, no notable ethical constraints, and without general anesthesia to the donor individuals. Furthermore, cryopreservation of DPSCs provides this opportunity for autologous transplantation in future studies without fundamental changes in stemness, viability, proliferation, and differentiating features. Current approaches for pulp tissue regeneration include pulp revascularization, cell-homing-based regenerative endodontic treatment (RET), cell-transplantation-based regenerative endodontic treatment, and allogeneic transplantation. In recent years, a novel technology, organoid, provides a mimic physiological condition and tissue construct that can be applied for tissue engineering, genetic manipulation, disease modeling, single-cell high throughput analysis, living biobank, cryopreserving and maintaining cells, and therapeutic approaches based on personalized medicine. The organoids can be a reliable preclinical prediction model for evaluating cell behavior, monitoring drug response or resistance, and comparing healthy and pathological conditions for therapeutic and prognostic approaches. In the current review, we focused on the promising application of 3D organoid technology based on DPSCs in oral and maxillofacial tissue regeneration. We discussed encountering challenges and limitations, and found promising solutions to overcome obstacles.

A 12-month randomized controlled trial to assess the efficacy of revitalization of retreated mature incisors with periapical radiolucency in adolescents

The use of regenrative endodontics is restoring the health status of the root canals of retreated mature teeth is a novel approach. Therefore, the current trial aimed to compare the effectiveness of regenerative endodontic procedures (REPs) to non-surgical root canal retreatment (NS-RCR) in reducing periapical radiolucency over one year for the retreatment of mature incisors with periapical periodontitis. The secondary purpose was to assess clinical success and regain pulp sensibility. A parallel randomized controlled trial, 66 mature incisors with periapical radiolucencies were randomly divided into two equal groups and retreated with either REPs or NS-RCR. At baseline and after 6 and 12 months, teeth were assessed clinically and radiographically using a periapical index (PAI). The Mann-Whitney test was used to analyze nonparametric PAI scores. The Electric pulp test readings were analyzed using the repeated measure analysis of variance (ANOVA). Over the follow-up intervals, there was no significant intergroup difference in the PAI medians, the majority of the teeth displayed a reduction in periapical radiolucency. At the end of the follow-up period, the clinical successes for the REP and NS-RCR groups were 93.9% and 97%, respectively (p = 0.555). Positive pulp sensibility was recorded in 54.54% of cases in the REPs after 12 months. Both approaches showed a comparable diminishing of periapical radiolucencies and equivalent clinical results. A conventional, non-surgical endodontic retreatment may not always be necessary.

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.

Next generation antibacterial strategies for regenerative endodontic procedures: A scoping review

BACKGROUND

The clinical results following regenerative endodontic procedures (REPs) vary according to numerous parameters, including the presence of bacteria. This limitation reduces the indications for REPs and calls for the development of next generation antibacterial strategies (NGAS) providing alternatives to current antibacterial strategies (CAS) such as double or triple antibiotic paste (DAP/TAP) and (Ca(OH)2).

OBJECTIVES

The present scoping review aims to describe the current trends regarding the use of such strategies and highlight future perspectives.

METHODS

Four databases (PUBMed, Cochrane, ClinicalTrials and Science Direct) were searched until 1st May 2023.

RESULTS

A total of 918 records were identified, 133 were screened and assessed for eligibility, and 87 articles were included. The findings show that (1) clinical studies are only available for CAS, (2) although next generation strategies are the most studied approach since 2017, they are all at the pre-clinical stage, (3) most of the next generation strategies use galenic forms which offer cell support and colonization and which simultaneously contain antibacterial molecules as alternatives to CAS and to antibiotics in general, (4) standardization is required for future research, specifically regarding the bacterial strains studied, the use of biofilm studies and the cellular behaviour assessments.

CONCLUSION

Although NGAS are promising strategies to improve REPs in the context of infection, the current evidence is mostly limited to pre-clinical studies. Further methodological improvement is required to allow relevant comparisons between studies and to reduce the time from bench to bedside.

Stem cells in regenerative dentistry: Current understanding and future directions

BACKGROUND

Regenerative dentistry aims to enhance the structure and function of oral tissues and organs. Modern tissue engineering harnesses cell and gene-based therapies to advance traditional treatment approaches. Studies have demonstrated the potential of mesenchymal stem cells (MSCs) in regenerative dentistry, with some progressing to clinical trials. This review comprehensively examines animal studies that have utilized MSCs for various therapeutic applications. Additionally, it seeks to bridge the gap between related findings and the practical implementation of MSC therapies, offering insights into the challenges and translational aspects involved in transitioning from preclinical research to clinical applications.

HIGHLIGHTS

To achieve this objective, we have focused on the protocols and achievements related to pulp-dentin, alveolar bone, and periodontal regeneration using dental-derived MSCs in both animal and clinical studies. Various types of MSCs, including dental-derived cells, bone-marrow stem cells, and umbilical cord stem cells, have been employed in root canals, periodontal defects, socket preservation, and sinus lift procedures. Results of such include significant hard tissue reconstruction, functional pulp regeneration, root elongation, periodontal ligament formation, and cementum deposition. However, cell-based treatments for tooth and periodontium regeneration are still in early stages. The increasing demand for stem cell therapies in personalized medicine underscores the need for scientists and responsible organizations to develop standardized treatment protocols that adhere to good manufacturing practices, ensuring high reproducibility, safety, and cost-efficiency.

CONCLUSION

Cell therapy in regenerative dentistry represents a growing industry with substantial benefits and unique challenges as it strives to establish sustainable, long-term, and effective oral tissue regeneration solutions.

An innovative cell-based transplantation therapy for an immature permanent tooth in an adult: a case report

BACKGROUND

Immature teeth with necrotic pulps present multiple challenges to clinicians. In such cases, regenerative endodontic procedures (REPs) may be a favorable strategy. Cells, biomaterial scaffolds, and signaling molecules are three key elements of REPs. Autologous human dental pulp cells (hDPCs) play an important role in pulp regeneration. In addition, autologous platelet concentrates (APCs) have recently been demonstrated as effective biomaterial scaffolds in regenerative dentistry, whereas the latest generation of APCs-concentrated growth factor (CGF), especially liquid phase CGF (LPCGF)-has rarely been reported in REPs.

CASE PRESENTATION

A 31-year-old woman presented to our clinic with the chief complaint of occlusion discomfort in the left mandibular posterior region for the past 5 years. Tooth #35 showed no pulp vitality and had a periodontal lesion, and radiographic examination revealed that the tooth exhibited extensive periapical radiolucency with an immature apex and thin dentin walls. REP was implemented via transplantation of autologous hDPCs with the aid of LPCGF. The periodontal lesion was managed with simultaneous periodontal surgery. After the treatment, the tooth was free of any clinical symptoms and showed positive results in thermal and electric pulp tests at 6- and 12-month follow-ups. At 12-month follow-up, radiographic evidence and three-dimensional models, which were reconstructed using Mimics software based on cone-beam computed tomography, synergistically confirmed bone augmentation and continued root development, indicating complete disappearance of the periapical radiolucency, slight lengthening of the root, evident thickening of the canal walls, and closure of the apex.

CONCLUSION

hDPCs combined with LPCGF represents an innovative and effective strategy for cell-based regenerative endodontics.

Neovascularization by DPSC-ECs in a Tube Model for Pulp Regeneration Study

The process of neovascularization during cell-based pulp regeneration is difficult to study. Here we developed a tube model that simulates root canal space and allows direct visualization of the vascularization process in vitro. Endothelial-like cells (ECs) derived from guiding human dental pulp stem cells (DPSCs) into expressing endothelial cell markers CD144, vWF, VEGFR1, and VEGFR2 were used. Human microvascular endothelial cells (hMVECs) were used as a positive control. DPSC-ECs formed tubules on Matrigel similar to hMVECs. Cells were mixed in fibrinogen/thrombin or mouse blood and seeded into wells of 96-well plates or injected into a tapered plastic tube (14 mm in length and 1 or 2 mm diameter of the apex opening) with the larger end sealed with MTA to simulate root canal space. Cells/gels in wells or tubes were incubated for various times in vitro and observed under the microscope for morphological changes. Samples were then fixed and processed for histological analysis to determine vessel formation. Vessel-like networks were observed in culture from 1 to 3 d after cell seeding. Cells/gels in 96-well plates were maintained up to 25 d. Histologically, both hMVECs and DPSC-ECs in 96-well plates or tubes showed intracellular vacuole formation. Some cells showed merged large vacuoles indicating the lumenization. Tubular structures were also observed resembling blood vessels. Cells appeared healthy throughout the tube except some samples (1 mm apical diameter) in the coronal third. Histological analysis also showed pulp-like soft tissue throughout the tube samples with vascular-like structures. hMVECs formed larger vascular lumen size than DPSC-ECs while the latter tended to have more lumen and tubular structure counts. We conclude that DPSC-ECs can form vascular structures and sustained in the 3-dimensional fibrin gel system in vitro. The tube model appears to be a proper and simple system simulating the root canal space for vascular formation and pulp regeneration studies.

Revolutionizing Endodontics: Innovative Approaches for Treating Mature Teeth With Closed Apices and Apical Lesions: A Report of Two Cases

INTRODUCTION

Modern tissue engineering strategies have elucidated the potential of regenerative endodontic treatment (RET) as an alternative for treating mature teeth.

METHODS

Here, we report two cases in which cell-based RET (CB-RET) using encapsulated allogeneic umbilical cord mesenchymal stem cells (UC-MSCs) in a platelet-poor plasma (PPP)-based scaffold was used in two mature teeth with pulp necrosis and apical periodontitis.

RESULTS

After 5 years of follow-up, the healing response was satisfactory in both cases, with evidence of pulp revitalization.

CONCLUSIONS

This is the first study to report the success of an extended, 5-year follow-up for allogeneic CB-RET. This report presents an innovative and sustainable solution to challenging endodontic scenarios.

Correlation between pulp sensibility and magnetic resonance signal intensity following regenerative endodontic procedures in mature necrotic teeth- a retrospective cohort study

BACKGROUND

With increasing studies being published on regenerative endodontic procedures (REPs) as a treatment modality for mature necrotic teeth, the assessment of outcomes following regenerative endodontic procedures has become more challenging and the demand for a better understanding of the regenerated tissues following this treatment is rising. The study aimed to correlate cold, electric pulp testing (EPT), and magnetic resonance imaging (MRI) signal intensity (SI) in mature necrotic teeth treated with regenerative endodontic procedures.

METHODOLOGY

This retrospective cohort study included eighteen adult patients who experienced tooth necrosis in mature maxillary anterior teeth recruited from the outpatient clinic, Conservative Dentistry Department, Faculty of Dentistry, Alexandria University, Alexandria, Egypt from July 2017 until December 2018 with 12 months of follow-up. regenerative endodontic procedures via blood clot were performed. The canals were instrumented by ProTaper Next (PTN) files until final sizes X3 or X5. Biodentine was used as cervical plug material. Pre and post-operative clinical follow-up was done where the patients' responses to cold and electric pulp testing were given a scoring system and were compared to the normal contralateral tooth. Pre and post-operative magnetic resonance imaging signal intensity of both the involved tooth and its contralateral at the middle and the apical thirds of the root canals were assessed after 3, 6, and 12 months. Data was analyzed using the ANOVA, Friedman and Bonferroni tests. Significance was set at a p-value < 0.05.

RESULTS

All 18 teeth scored a baseline score of "2" for cold and electric pulp testing. There was a significant difference between scores of the cold test at baseline and 12-month follow-up (p < 0.001). There was a significant difference between scores of the electric pulp testing of baseline and 12-month follow-up (p < 0.001). There was a moderately significant indirect (inverse) correlation between magnetic resonance imaging signal intensity and cold test in both the middle and apical thirds at 12 months. No significant correlations were detected between magnetic resonance imaging signal intensity and electric pulp testingat any of the time intervals (p > 0.05).

CONCLUSION

Magnetic resonance imaging is a successful non-invasive method to assess outcomes of regenerative endodontic procedures and correlating it with another reliable method of assessing pulpal responses, cold test, could validate these outcomes.

CLINICAL TRIAL REGISTRATION

The study was registered with ClinicalTrials.gov (ID: NCT03804450).

Exosomes as Promising Therapeutic Tools for Regenerative Endodontic Therapy

Pulpitis is a common and frequent disease in dental clinics. Although vital pulp therapy and root canal treatment can stop the progression of inflammation, they do not allow for genuine structural regeneration and functional reconstruction of the pulp-dentin complex. In recent years, with the development of tissue engineering and regenerative medicine, research on stem cell-based regenerative endodontic therapy (RET) has achieved satisfactory preliminary results, significantly enhancing its clinical translational prospects. As one of the crucial paracrine effectors, the roles and functions of exosomes in pulp-dentin complex regeneration have gained considerable attention. Due to their advantages of cost-effectiveness, extensive sources, favorable biocompatibility, and high safety, exosomes are considered promising therapeutic tools to promote dental pulp regeneration. Accordingly, in this article, we first focus on the biological properties of exosomes, including their biogenesis, uptake, isolation, and characterization. Then, from the perspectives of cell proliferation, migration, odontogenesis, angiogenesis, and neurogenesis, we aim to reveal the roles and mechanisms of exosomes involved in regenerative endodontics. Lastly, immense efforts are made to illustrate the clinical strategies and influencing factors of exosomes applied in dental pulp regeneration, such as types of parental cells, culture conditions of parent cells, exosome concentrations, and scaffold materials, in an attempt to lay a solid foundation for exploring and facilitating the therapeutic strategy of exosome-based regenerative endodontic procedures.

Cell-Based Regenerative Endodontics for the Treatment of Irreversible Pulpitis: AnIn VivoInvestigation

INTRODUCTION

This study aims to investigate the ability of umbilical cord mesenchymal stem cells (UC-MSC) to enhance the regeneration of pulp-dentin complex in immature permanent teeth with irreversible pulpitis.

METHODS

A total of 32 mandibular premolar teeth with immature apices in 5 dogs were used in this in-vivo randomized controlled trial (RCT). Eight healthy teeth without pre-existing pathosis served as the positive control samples and received no treatment, while in another 8 teeth, the pulp was completely extirpated (negative control). Class V cavities were prepared to induce inflammation in the remaining 16 teeth (groups 3 and 4) and the pulp was extirpated 2-4 mm short of the radiographic apex. Of the 16, the 8 teeth in group 4 received 1 mL of cord blood stem cells with a hydrogel scaffold. Blood clots were covered with mineral trioxide aggregates at the cementoenamel junction in the experimental groups, and teeth were filled with RMGI and composite. Three months later, block sections were removed for histologic evaluations for the evaluation of postoperative apical closure, degree of inflammation, and presence of normal pulp tissue. The data were statistically analyzed with the chi-square test (P < .05).

RESULTS

All teeth with complete pulp extirpation demonstrated pulpal necrosis with no postoperative closure of their apices, while apical closure was seen in all the teeth in the remaining groups. There was a statistically significant (P < .001) difference in the presence of inflammation and normal pulp tissue between the experimental groups. The teeth in group 3 showed normal pulp tissue extending to the level of MTA, but there was inflammation within the canal space. In contrast, the teeth in the UC-MSC group demonstrated organized, normal pulp tissue with no inflammation.

CONCLUSION

Based on these results, the regeneration of the pulp-dentin complex is possible with no inflammation when UC-MSCs are used and 2-4 mm of the apical pulp remains intact in immature teeth with irreversible pulpitis.

Pulp Regenerative Therapy Using Autologous Dental Pulp Stem Cells in a Mature Tooth with Apical Periodontitis: A Case Report

The utility and feasibility of pulp regenerative therapy with autologous dental pulp stem cells (DPSCs) in mature teeth with irreversible pulpitis were clinically demonstrated. On the other hand, there is no evidence of the utility of DPSCs in mature teeth with apical periodontitis. The aim of this case report was to describe the potential utility of regenerative cell therapy in mature teeth with apical periodontitis. A 44-year-old man was referred for pulp regeneration due to a periapical lesion in his maxillary first premolar. Root canal disinfection was performed by irrigation and intracanal medication by nanobubbles with levofloxacin and amphotericin B in addition to conventional irrigation. Autologous DPSCs isolated from an extracted third molar were transplanted into the root canal after residual bacteria and fungi were below the detection level by polymerase chain reaction assay using universal genes to amplify specific regions within bacterial 16S ribosomal DNA and fungal ribosomal DNA (ITS1), respectively. There were no adverse events or systemic toxicity assessed for clinical evaluations during the 79-week-follow-up period and laboratory evaluations after 4 weeks. The affected tooth was responsive to the electric pulp test. Cone-beam computed tomographic imaging revealed a reduced lesion size, remission of the periapical tissue, and mineralized tissue formation in the apical part of the canal after 79 weeks. The signal intensity on magnetic resonance imaging of the regenerated tissue in the affected tooth was comparable to that of the normal pulp in the adjacent teeth after 24 weeks. This case report demonstrated the potential use of DPSCs for pulp regenerative therapy in mature teeth with apical periodontitis.

Advances in Regenerative Dentistry Approaches: An Update

Regenerative dentistry is a rapidly evolving field in dentistry, which has been driven by advancements in biomedical engineering research and the rising treatment expectations and demands that exceed the scope of conventional approaches. Tissue engineering, the foundation of regenerative dentistry, mainly focuses on 3 key components: stem cells, bioactive molecules, and scaffolds. Dental tissue-derived stem cells are especially significant in this regard due to their remarkable properties. Regenerative techniques have provided novel approaches to many conventional treatment strategies in various disciplines of dentistry. For instance, regenerative endodontic procedures such as pulp revascularisation have provided an alternative approach to conventional root canal treatment. In addition, conventional surgical and nonsurgical periodontal treatment is being taken over by modified approaches of guided tissue regeneration with the aid of 3-dimensional bioprinting and computer-aided design, which has revolutionised oral and maxillofacial tissue engineering. This review presents a concise overview of the latest treatment strategies that have emerged into clinical practice, potential future technologies, and the role of dental tissue-derived stem cells in regenerative dentistry.

Periapical bacterial disinfection is critical for dental pulp regenerative cell therapy in apical periodontitis in dogs

BACKGROUND

Application of pulp regenerative cell therapy for mature teeth with periapical lesions is a critical clinical challenge. The bacterial infection in inaccessible location within the root canal system and in the periapical lesions could cause resistance and impediment, leading to limitations in successful therapy. Thus, the aim of this study was to examine the effect of residual bacteria on the outcome of pulp regeneration in mature teeth with apical periodontitis in dogs.

METHODS

Periapical lesions were induced in 32 root canals of 4 dogs in two different models in severities, model A and model B. Model A (moderate infection): the canal exposed to the oral cavity for 2 weeks and then closed for 2 weeks. Model B (severe infection): the canal exposed to the oral cavity for 2 months and then closed for 5 months. All root canals were irrigated with 6% sodium hypochlorite, and 3% EDTA and further with 0.015% levofloxacin-containing nanobubbles, which was also used as an intracanal medicament. The aseptic conditions were examined by bacterial anaerobic culture and/or PCR analyses. The root canal treatment was repeated several times, and allogeneic dental pulp stem cells were transplanted into the root canals. The radiographic evaluation of periapical lesions was performed by cone-beam computed tomography before the first treatment, just after cell transplantation, and after 2 months and 6 months in both model A, model B, respectively. The animals were then sacrificed and the jaw blocks were harvested for histological and histobacteriological evaluations of pulp regeneration and periapical tissue healing. Furthermore, the DiI-labelled DPSCs were transplanted into the root canals after complete disinfection (n = 4) or without root canal treatment (n = 4) in the apical periodontitis model (model A) in one dog, and cell localization was compared 72 h after transplantation.

RESULTS

In 8 out of 12 canals from model A, and 10 out of 15 canals from model B, pulp regeneration with good vascularization, innervation, and a significant reduction in the radiolucent area of the periapical lesions were observed. However, in the other 4 canals and 5 canals from model A and model B, respectively, no pulp tissue was regenerated, and inflammation in the periapical tissue, and external resorption or healed external resorption were detected. The presence of residual bacteria in the periapical tissues and severe inflammation were significantly associated with inhibition of regenerated pulp tissue in these 9 unsuccessful canals (P < 0.05, each) (OR = 0.075, each) analyzed by multiple logistic regression analysis. For cellular kinetics, transplanted cells remained in the disinfected root canals, while they were not detected in the infected root canals, suggesting their migration through the apical foramen under the influence of inflammation.

CONCLUSIONS

A true pulp-dentin complex was regenerated in the root canal by the pulp regenerative therapy in mature teeth with apical lesions. The successful pulp regeneration was negatively associated both with residual bacteria and inflammation in the periapical tissue.

Treatment outcomes of regenerative endodontic procedures in nonvital mature permanent teeth: a retrospective study

OBJECTIVES

This retrospective study was undertaken to clinically and radiographically evaluate the long-term outcomes of regenerative endodontic procedures (REPs) for nonvital mature permanent teeth, to analyze predictors influencing treatment outcomes.

METHODS

Nonvital mature permanent teeth treated by REPs with a minimum follow-up period of 6 months were included from 2015 to 2017. Treatment outcomes were categorized as success and failure. The periapical status and lesion healing were assessed in terms of the periapical index (PAI) and the percentage changes in periapical radiolucency (PARL) area. The clinical and radiographic outcomes of REPs were assessed by Mann-Whitney test at different follow-up period. Kaplan-Meier curves and Univariate Cox regression analysis were conducted to assess the success and identify potential predictors affecting outcomes, respectively.

RESULTS

A total of 37 mature teeth with an average follow-up of 4.3 years satisfied the criteria, and 89.2% of the teeth had a successful outcome. Significant differences in PAI scores were found between each period with respect to the baseline (p < .05). Among different periods, there was a significant difference between intervals of 3-6 months and 7-12 months (p = .039) and no significant difference between each interval of more than 12 months (p > .05). Eighty-seven percent of teeth with preoperative PARL presented completely healed. REPs significantly decreased the PARL area at the interval of 7-12 months compared to 3-6 months (p = .025), with no significant difference between each interval of more than 12 months (p > .05). No significant predictor was found for the success of outcome (p > .05). Thirteen teeth (35.1%) regained pulp sensibility, and 40.5% of the teeth exhibited intracanal calcification.

CONCLUSIONS

Within the limitations of this study, REPs provided a high long-term success rate and promoted the resolution of PARL as a biologically-based alternative treatment option for nonvital mature teeth.

CLINICAL RELEVANCE

REPs provide a high long-term success rate and promoted healing of apical periodontitis comparable with reported outcomes for root canal therapy of mature teeth.

Implications of root, pulp chamber, and canal anatomy on pulpotomy and revitalization procedures

OBJECTIVES

This review aims to discuss the implications of anatomy of the root, pulp chamber, and canals on pulpotomy and revitalization procedures (RPs) as treatment alternatives to root canal treatment procedures.

METHODS

This narrative review was undertaken to address two main questions - why remove vital pulp tissue in teeth with complex canal anatomy when it can be preserved? And why replace the necrotic pulp in teeth with mature roots with a synthetic material when we can revitalize? This review also aims to discuss anatomical challenges with pulpotomy and revitalization procedures.

RESULTS

Maintaining the vitality of the pulp via partial or full pulpotomy procedures avoids the multiple potential challenges faced by clinicians during root canal treatment. However, carrying out pulpotomy procedures requires a meticulous understanding of the pulp chamber anatomy, which varies from tooth to tooth. Literature shows an increased interest in the application of RPs in teeth with mature roots; however, to date, the relation between the complexity of the root canal system and outcomes of RPs in necrotic multi-rooted teeth with mature roots is unclear and requires further robust comparative research and long-term follow-up.

CONCLUSIONS

Whenever indicated, pulpotomy procedures are viable treatment options for vital teeth with mature roots; however, comparative, adequately powered studies with long-term follow-up are needed as a priority in this area. RPs show promising outcomes for necrotic teeth with mature roots that warrant more evidence in different tooth types with long-term follow-ups.  CLINICAL RELEVANCE: Clinicians should be aware of the pulp chamber anatomy, which is subject to morphological changes by age or as a defensive mechanism against microbial irritation, before practicing partial and full pulpotomy procedures. RP is a promising treatment option for teeth with immature roots, but more evidence is needed for its applications in teeth with mature roots. A universal consensus and considerably more robust evidence are needed for the standardization of RPs in teeth with mature roots.

Advancing Dentistry through Bioprinting: Personalization of Oral Tissues

Despite significant advancements in dental tissue restoration and the use of prostheses for addressing tooth loss, the prevailing clinical approaches remain somewhat inadequate for replicating native dental tissue characteristics. The emergence of three-dimensional (3D) bioprinting offers a promising innovation within the fields of regenerative medicine and tissue engineering. This technology offers notable precision and efficiency, thereby introducing a fresh avenue for tissue regeneration. Unlike the traditional framework encompassing scaffolds, cells, and signaling factors, 3D bioprinting constitutes a contemporary addition to the arsenal of tissue engineering tools. The ongoing shift from conventional dentistry to a more personalized paradigm, principally under the guidance of bioprinting, is poised to exert a significant influence in the foreseeable future. This systematic review undertakes the task of aggregating and analyzing insights related to the application of bioprinting in the context of regenerative dentistry. Adhering to PRISMA guidelines, an exhaustive literature survey spanning the years 2019 to 2023 was performed across prominent databases including PubMed, Scopus, Google Scholar, and ScienceDirect. The landscape of regenerative dentistry has ushered in novel prospects for dentoalveolar treatments and personalized interventions. This review expounds on contemporary accomplishments and avenues for the regeneration of pulp-dentin, bone, periodontal tissues, and gingival tissues. The progressive strides achieved in the realm of bioprinting hold the potential to not only enhance the quality of life but also to catalyze transformative shifts within the domains of medical and dental practices.

Effectiveness of root canal filling materials and techniques for treatment of apical periodontitis: A systematic review

BACKGROUND

Apical periodontitis (AP) is an inflammatory disease of the apical periodontium as sequelae of pulp death. It is managed by disinfection and filling of the root canal space.

OBJECTIVES

The aim of this systematic review was to investigate whether obturation techniques and materials used for root canal filling led to the management of AP.

METHODS

A systematic review protocol was written following the preferred reporting items for systematic reviews and meta-analyses (PRISMA) checklist and registered on the international prospective register of systematic reviews (PROSPERO; CRD42021260275) including two populations, interventions, comparisons, outcomes and time (PICOT) for the research questions querying the effectiveness of obturation techniques (PICOT 1) and materials (PICOT 2) for the management of AP. Electronic searches were conducted on PubMed, ScienceDirect, Scopus and Embase search engines. Searches on International Endodontic Journal, Journal of Endodontics, Clinical Oral Investigations, Journal of Dental Research and Journal of Dentistry websites were also conducted, until May 2021. Both primary (tooth survival) and secondary outcomes were evaluated. The risk of bias was assessed by Cochrane RoB2 for the randomized and ROBINS-I for the nonrandomized trials.

RESULTS

The search strategy identified 1652 studies, with 1600 excluded on the title and abstract screening, leaving 52 studies for full-text screening. In total, 10 studies met the inclusion criteria. The obturation technique and materials used did not affect the outcome of AP. Vertical compaction resulted in faster resolution of periapical lesions. The oral health-related quality of life of patients treated with lateral condensation exhibited poorer outcomes compared with single matched cone after 6 months of recall.

DISCUSSION

The inclusion and exclusion criteria used for this systematic review enabled the capture of all the literature available on the effect of obturation techniques and materials on the outcome of AP. The data were heterogenous, and a number of articles investigating obturation techniques had no information on the materials and techniques used as they looked at the quality of fill.

CONCLUSIONS

Included studies did not find any difference between different procedures (PICOT 1) and materials (PICOT 2). The risk of bias was high, thus the findings should be interpreted with caution.

REGISTRATION

PROSPERO registration number: CRD42021260275.

Effectiveness of endodontic tissue engineering in treatment of apical periodontitis: A systematic review

BACKGROUND

Regenerative endodontics has evolved in recent years with tissue engineering concepts in particular appearing promising. Endodontic tissue engineering (ETE) describes the various approaches based on the orthograde introduction of scaffolds or biomaterials (with or without cells) into the root canal to achieve pulp tissue regeneration. There are currently no systematic reviews investigating whether ETE is a suitable method for the treatment of endodontic disease in both mature and immature permanent teeth.

OBJECTIVES

The purpose of this systematic review was to determine the effectiveness of ETE in permanent teeth with pulp necrosis in comparison with conventional endodontic treatment.

METHODS

We searched MEDLINE, Embase and the Cochrane Library for published reports as well as Google Scholar for grey literature up to November 2021. Included were studies of patients with permanent immature or mature teeth and pulp necrosis with or without signs of apical periodontitis (P) comparing ETE (I) with calcium hydroxide apexification, apical plug and root canal treatment (C) in terms of tooth survival, pain, tenderness, swelling, need for medication (analgesics and antibiotics), radiographic evidence of reduction in apical lesion size, radiographic evidence of normal periodontal ligament space, function (fracture and restoration longevity), the need for further intervention, adverse effects (including exacerbation, restoration integrity, allergy and discolouration), oral health-related quality of life (OHRQoL), presence of sinus tract and response to sensibility testing (O). An observation period of at least 12 months was mandatory (T) and the number of patients in human experimental studies or longitudinal observational studies had to be at least 20 (10 in each arm) at the end (S). Risk of bias was appraised using the Cochrane risk-of-bias (RoB 2) tool. Two authors independently screened the records, assessed full texts for eligibility and evaluated risk of bias. Heterogeneity of outcomes and limited body of evidence did not allow for meta-analysis.

RESULTS

Two randomized clinical trials investigating cell transplantation approaches with a total of 76 participants (40 treated immature teeth and 36 treated mature teeth) were included for qualitative analysis. Both studies had moderate concerns in terms of risk of bias. Due to the lack of homogeneity a meta-analysis was not possible. Tooth survival for ETE, root canal treatment and apexification was 100% after 12 months. Teeth treated with ETE showed a higher number of cases with positive pulpal responses to sensitivity tests and with blood perfusion compared with root canal treatment or apexification.

DISCUSSION

This systematic review highlights that there is limited evidence for ETE approaches. Even though the results of this review suggest a high survival with ETE in mature and immature teeth, there is a moderate risk of bias due to methodological limitations in the included studies, so the overall results should be interpreted with caution. Lack of a robust control group was a common problem during literature screening, and outcomes besides dental survival were reported inconsistently. Future clinical trials need to address methodical as well as assessment concerns and report long-term results.

CONCLUSION

The benefits and high survival rates reported for ETE techniques suggest that this procedure might be an alternative to conventional procedures for permanent teeth with pulpal necrosis. However, more appropriate studies are needed to derive clinical recommendations.

REGISTRATION

PROSPERO (CRD42021266350).

Treatment of pulpal and apical disease: The European Society of Endodontology (ESE) S3-level clinical practice guideline

BACKGROUND

The ESE previously published quality guidelines for endodontic treatment in 2006; however, there have been significant changes since not only in clinical endodontics but also in consensus and guideline development processes. In the development of the inaugural S3-level clinical practice guidelines (CPG), a comprehensive systematic and methodologically robust guideline consultation process was followed in order to produce evidence-based recommendations for the management of patients presenting with pulpal and apical disease.

AIM

To develop an S3-level CPG for the treatment of pulpal and apical disease, focusing on diagnosis and the implementation of the treatment approaches required to manage patients presenting with pulpitis and apical periodontitis (AP) with the ultimate goal of preventing tooth loss.

METHODS

This S3-level CPG was developed by the ESE, with the assistance of independent methodological guidance provided by the Association of Scientific Medical Societies in Germany and utilizing the GRADE process. A robust, rigorous and transparent process included the analysis of relevant comparative research in 14 specifically commissioned systematic reviews, prior to evaluation of the quality and strength of evidence, the formulation of specific evidence and expert-based recommendations in a structured consensus process with leading endodontic experts and a broad base of external stakeholders.

RESULTS

The S3-level CPG for the treatment of pulpal and apical disease describes in a series of clinical recommendations the effectiveness of diagnosing pulpitis and AP, prior to investigating the effectiveness of endodontic treatments in managing those diseases. Therapeutic strategies include the effectiveness of deep caries management in cases with, and without, spontaneous pain and pulp exposure, vital versus nonvital teeth, the effectiveness of root canal instrumentation, irrigation, dressing, root canal filling materials and adjunct intracanal procedures in the management of AP. Prior to treatment planning, the critical importance of history and case evaluation, aseptic techniques, appropriate training and re-evaluations during and after treatment is stressed.

CONCLUSION

The first S3-level CPG in endodontics informs clinical practice, health systems, policymakers, other stakeholders and patients on the available and most effective treatments to manage patients with pulpitis and AP in order to preserve teeth over a patient's lifetime, according to the best comparative evidence currently available.

Effectiveness of revitalization in treating apical periodontitis: A systematic review and meta-analysis

BACKGROUND

Revitalization procedures primarily aim to eliminate clinical symptoms and heal periapical lesions.

OBJECTIVES

The objective of the study was to elucidate the effectiveness of revitalization in treating apical periodontitis in necrotic mature and immature permanent teeth based on the following PICO question: In patients with permanent immature or mature teeth and pulp necrosis with or without signs of apical periodontitis (P) what is the effectiveness of revitalization (I) in comparison with calcium hydroxide apexification, apical plug and root canal treatment (C) in terms of tooth survival, pain, tenderness, swelling, need for medication (analgesics and antibiotics), radiographic evidence of reduction of apical lesion size, radiographic evidence of normal periodontal ligament space, radiographic evidence of increased root thickness and length (not for mature teeth), tooth function (fracture and restoration longevity), need for further intervention, adverse effects (including exacerbation, restoration integrity, allergy and discolouration), oral health-related quality of life (OHRQoL), presence of sinus tract and response to sensibility testing (O). (T) = Defined as a minimum of 1 year and maximum of as long as possible for all outcome measures, except 'pain, tenderness, swelling, need for medication (analgesics)', which is a minimum of 7 days and maximum of 3 months and OHRQoL which is minimum of 6 months and a maximum of as long as possible.

METHODS

Three databases (PubMed, Embase and Cochrane Library) were searched for human, experimental and observational studies in English, complemented with hand search, until 31/10/2021. Studies recruiting teeth with pulp necrosis (with/without apical periodontitis), with minimum 10 teeth/arm at the end of the study and with a follow-up of at least 1 year, were included. Records without an abstract and a full text were excluded. The qualitative analysis of the included (non-) randomized controlled clinical trials was performed with the Revised Cochrane risk-of-bias tools (RoB 2 and ROBINS-I). Meta-analysis for survival and success (including a subgroup analysis for mature/immature permanent teeth) was performed using the Mantel-Haenszel method. The certainty of evidence was assessed using GRADE (Grades of Recommendation, Assessment, Development and Evaluation).

RESULTS

From the 365 identified records, five met the inclusion criteria. The 12 months survival rate was 100% for all (im)mature permanent teeth in all groups (3 studies). The success rate at 12 months was 100% for immature permanent teeth for I and C (1 study), however, reduced to 92% and 80% for mature teeth in I and C respectively (1 study, p > .05). The risk of bias for the most critical outcome (survival) was high for two studies and low for one. For the critical outcome success, all assessed studies were highly biased. Meta-analyses provided pooled relative risk with no statistically significant difference between I and C for both survival (RR = 1.00, 95%CI = 0.96-1.04, p = 1.00) and success (RR = 1.06; 95%CI = 0.83-1.35, p = .66). The evidence level for survival was kept 'low' and for success was downgraded to 'very low' due to inconsistency and imprecision.

DISCUSSION

The survival and success rates were favourable in all included studies and for all groups; however, these outcomes are not reliable due to the low certainty level. Clinically, the most reported adverse event was tooth discolouration, hence the application of bismuth oxide containing calcium silicate cements should be avoided in revitalization. Radiographically, caution is needed when assessing periapical bone healing and further root development with periapical radiographs, due to multifactorial inaccuracies of this imaging technique. Methodological and assessment concerns need to be addressed in future clinical trials. Long-term results are necessary for studies reporting revitalization of mature permanent teeth, as they seem to be experimental so far.

CONCLUSIONS

No robust evidence was discovered to support that revitalization is effective to treat apical periodontitis in (im)mature permanent teeth. The success and survival rates of revitalized and fully pulpectomized (im)mature permanent teeth did not differ significantly.

REGISTRATION

Prospero: CRD42021262466.

Engineering the Future of Dental Health: Exploring Molecular Advancements in Dental Pulp Regeneration

Protected by the surrounding mineralized barriers of enamel, dentin, and cementum, dental pulp is a functionally versatile tissue that fulfills multiple roles [...].

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.

Dental Pulp Stem Cells for Salivary Gland Regeneration-Where Are We Today?

Xerostomia is the phenomenon of dry mouth and is mostly caused by hypofunction of the salivary glands. This hypofunction can be caused by tumors, head and neck irradiation, hormonal changes, inflammation or autoimmune disease such as Sjögren's syndrome. It is associated with a tremendous decrease in health-related quality of life due to impairment of articulation, ingestion and oral immune defenses. Current treatment concepts mainly consist of saliva substitutes and parasympathomimetic drugs, but the outcome of these therapies is deficient. Regenerative medicine is a promising approach for the treatment of compromised tissue. For this purpose, stem cells can be utilized due to their ability to differentiate into various cell types. Dental pulp stem cells are adult stem cells that can be easily harvested from extracted teeth. They can form tissues of all three germ layers and are therefore becoming more and more popular for tissue engineering. Another potential benefit of these cells is their immunomodulatory effect. They suppress proinflammatory pathways of lymphocytes and could therefore probably be used for the treatment of chronic inflammation and autoimmune disease. These attributes make dental pulp stem cells an interesting tool for the regeneration of salivary glands and the treatment of xerostomia. Nevertheless, clinical studies are still missing. This review will highlight the current strategies for using dental pulp stem cells in the regeneration of salivary gland tissue.

Immunomodulatory Mechanism and Potential Application of Dental Pulp-Derived Stem Cells in Immune-Mediated Diseases

Dental pulp stem cells (DPSCs) are mesenchymal stem cells (MSCs) derived from dental pulp tissue, which have high self-renewal ability and multi-lineage differentiation potential. With the discovery of the immunoregulatory ability of stem cells, DPSCs have attracted much attention because they have similar or even better immunomodulatory effects than MSCs from other sources. DPSCs and their exosomes can exert an immunomodulatory ability by acting on target immune cells to regulate cytokines. DPSCs can also migrate to the lesion site to differentiate into target cells to repair the injured tissue, and play an important role in tissue regeneration. The aim of this review is to summarize the molecular mechanism and target cells of the immunomodulatory effects of DPSCs, and the latest advances in preclinical research in the treatment of various immune-mediated diseases, providing new reflections for their clinical application. DPSCs may be a promising source of stem cells for the treatment of immune-mediated diseases.

Banking of perinatal mesenchymal stem/stromal cells for stem cell-based personalized medicine over lifetime: Matters arising

Mesenchymal stromal/stem cells (MSCs) are currently applied in regenerative medicine and tissue engineering. Numerous clinical studies have indicated that MSCs from different tissue sources can provide therapeutic benefits for patients. MSCs derived from either human adult or perinatal tissues have their own unique advantages in their medical practices. Usually, clinical studies are conducted by using of cultured MSCs after thawing or short-term cryopreserved-then-thawed MSCs prior to administration for the treatment of a wide range of diseases and medical disorders. Currently, cryogenically banking perinatal MSCs for potential personalized medicine for later use in lifetime has raised growing interest in China as well as in many other countries. Meanwhile, this has led to questions regarding the availability, stability, consistency, multipotency, and therapeutic efficiency of the potential perinatal MSC-derived therapeutic products after long-term cryostorage. This opinion review does not minimize any therapeutic benefit of perinatal MSCs in many diseases after short-term cryopreservation. This article mainly describes what is known about banking perinatal MSCs in China and, importantly, it is to recognize the limitation and uncertainty of the perinatal MSCs stored in cryobanks for stem cell medical treatments in whole life. This article also provides several recommendations for banking of perinatal MSCs for potentially future personalized medicine, albeit it is impossible to anticipate whether the donor will benefit from banked MSCs during her/his lifetime.

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.

Decellularized rat submandibular gland as an alternative scaffold for dental pulp regeneration

Introduction: Decellularized extracellular matrix has been recognized as an optimal scaffold for dental pulp regeneration. However, the limited amount of native dental pulp tissue restricts its clinical applications. The submandibular gland shares some basic extracellular matrix components and characteristics with dental pulp. However, whether decellularized submandibular gland extracellular matrix (DSMG) can be used as an alternative scaffold for dental pulp regenerative medicine is unclear. Methods: Thus, we successfully decellularized the whole rat submandibular gland and human dental pulp, and then conducted in vitro and in vivo studies to compare the properties of these two scaffolds for dental pulp regeneration. Results: Our results showed that extracellular matrix of the submandibular gland had great similarities in structure and composition with that of dental pulp. Furthermore, it was confirmed that the DSMG could support adhesion and proliferation of dental pulp stem cells in vitro. In vivo findings revealed that implanted cell-seeded DSMG formed a vascularized dental pulp-like tissue and expressed markers involved in dentinogenesis and angiogenesis. Discussion: In summary, we introduced a novel accessible biological scaffold and validated its effectiveness as an extracellular matrix-based tissue engineering scaffold for dental pulp regenerative therapy.

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.

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.

Outcomes reporting in systematic reviews on revitalization: A scoping review for the development of a core outcome set

BACKGROUND

Revitalization is a type of regenerative endodontic treatment (RET) that offers the exciting prospect of revitalizing damaged tissue, therefore improving outcomes for non-vital immature teeth. To evaluate its potential, there needs to be consistency in outcome reporting of clinical studies investigating revitalization to allow for evidence synthesis and inform clinical decision making.

OBJECTIVES

The aim of this scoping review was to identify outcomes that are reported in systematic reviews on revitalization including how and when these outcomes are measured. Additionally, evidence of selective reporting bias in the reviews was assessed.

METHODS

A comprehensive electronic search of healthcare databases and grey literature was conducted to identify systematic reviews published in the English language reporting outcomes of revitalization in permanent immature teeth. There was no restriction on the date of publication. Outcome data was extracted by four reviewers independently and mapped with a healthcare taxonomy into five core areas: survival, clinical/physiological changes, life impact, resource use and adverse events. Selective reporting bias and how it was measured was assessed independently by two reviewers.

RESULTS

Twenty-six systematic reviews were included in this scoping review. There was lack of standardization in reporting and significant heterogeneity across reviews in outcome endpoints. The outcomes reported could be aligned within the five core areas of the taxonomy including tooth survival which was reported in nine reviews. Patient-reported outcomes were generally limited and no review reported on Oral Health Related Quality of Life. Many of the reviews reporting on randomized control trials were at low risk of selective reporting bias whilst other study designs were at higher risk.

DISCUSSION

Consistency in outcome reporting is necessary to realize the benefits of old but particularly novel therapies. Data from this review confirmed heterogeneity in reporting outcomes of revitalization and the need for development of a core outcome set (COS).

CONCLUSIONS

Several important outcomes including survival, root development, tooth discolouration and periapical healing have been identified in this review which could inform the development of a COS in this area.

REGISTRATION

Core Outcome Measures in Effectiveness Trials (COMET) database (registration no. 1879).

A Compilation of Study Models for Dental Pulp Regeneration

Efforts to heal damaged pulp tissue through tissue engineering have produced positive results in pilot trials. However, the differentiation between real regeneration and mere repair is not possible through clinical measures. Therefore, preclinical study models are still of great importance, both to gain insights into treatment outcomes on tissue and cell levels and to develop further concepts for dental pulp regeneration. This review aims at compiling information about different in vitro and in vivo ectopic, semiorthotopic, and orthotopic models. In this context, the differences between monolayer and three-dimensional cell cultures are discussed, a semiorthotopic transplantation model is introduced as an in vivo model for dental pulp regeneration, and finally, different animal models used for in vivo orthotopic investigations are presented.