Human dental pulp stem cells (hDPSCs) are a promising cell source for tooth regeneration therapies. However, conventional culture scaffold materials are often animal-derived, leading to immunogenicity concerns and limited availability. In this study, we explored phosphorylated cellulose nanofibers (P-CNFs), which have a fine fiber morphology and phosphate groups, as a novel scaffold material for cell culture. Immortalized hDPSCs were cultured on P-CNF scaffolds with different phosphate contents (0-1.42 mmol g-1) prepared by varying the molar ratio of urea and diammonium hydrogen phosphate and the reaction time. Cells cultured on unmodified CNFs exhibited poor adhesion and formed spheroids, indicating low bioadaptability. In contrast, P-CNF scaffolds with moderate phosphate content (0.54-0.78 mmol g-1) significantly improved cell adhesion; further increases in phosphate content decreased cell adhesion, indicating a strong dependence on phosphate content. Intriguingly, even in the absence of differentiation inducers, hDPSCs on P-CNF scaffolds with an optimal phosphate content of 0.78 mmol g-1 showed equal or higher expression of hard tissue marker genes compared to collagen scaffolds with differentiation inducers, suggesting that P-CNFs can directly promote hard tissue differentiation. These findings highlight plant-derived, animal-free P-CNFs as a promising biomaterial for advanced dental tissue engineering.

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.

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.

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.

Cell-based pulp regeneration utilizes capping materials underneath a final restoration to seal the tooth after delivering cells into the canal system. Studying the immediate biocompatibility of materials with injected cells has been challenging. This study aimed to utilize a tube model to observe cell response directly and conveniently to the capping materials in a cell culture in vitro system.

A tapered plastic tube (14 mm in length, 2 mm diameter of the apex opening) to simulate root canal space was filled with fluorescence-labeled dental pulp cells mixed in fibrin gel and the larger end sealed with various capping materials including MTA, Biodentine, hydroxyapatite-tricalcium phosphate (HA-TCP), composite and glass ionomer. The tube was placed in wells of culture plates and incubated for various times in vitro and observed under the microscope for cell morphological changes. pH changes within the tube were monitored over time.

Both fresh MTA and Biodentine caused adverse response to the cells in the tube. Only a few normal growing cells were observed at the apical end. Composite or glass ionomer appeared better tolerated by cells. HA-TCP mixed in fibrin gel demonstrated the highest compatibility with cells, however, using HA-TCP to separate cells from fresh MTA or Biodentine did not reduce the negative effect of these two calcium silicate cements. The pH increased within the tube may explain the observed toxicity.

Using HA-TCP mixed in fibrin gel as a capping material appears highly biocompatible to cells while fresh MTA and Biodentine are not.

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

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

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

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

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.

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.

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.

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.

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.

Magnetic resonance imaging (MRI) has recently emerged as a promising modality for dental applications, offering radiation-free imaging with superior soft tissue visualization capabilities compared to x-ray-based techniques such as spiral or cone beam computed tomography (CBCT). Conventional radiographic methods or CBCT cannot directly assess the condition of the dental pulp due to their primary focus on hard tissue visualization, whereas the dental pulp is primarily composed of connective tissue. Given the advantages of MRI in soft tissue imaging, this review aims to explore the current application of MRI for dental pulp tissue assessment. Relevant studies concerning the application of MRI for visualizing dental pulp were retrieved from databases including PubMed, Embase, and Scopus. The review explored and discussed the advancements in MRI hardware and software related to dental pulp visualization, as well as the advantages and limitations of MRI in dental pulp studies. Despite remaining limitations, such as scanning time and cost considerations, MRI offers notable benefits, including radiation-free imaging and potentially superior resolution and accuracy compared with other imaging techniques. Consequently, the continued advancement of MRI as a noninvasive diagnostic method in dentistry, particularly for assessing pulp condition, holds substantial promise for improving endodontic diagnosis and subsequent treatment decision-making.

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.

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.

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.

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.

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 protocol introduces a novel multi-chamber bioreactor tailored for ex-vivo cell culture in dentistry research, emulating the 3D dental environment to propel research in dental applications. Constructed primarily from a polymeric material with a sophisticated 3D design, the bioreactor securely holds teeth structures within sealed chambers, enabling controlled perfusion of culture medium crucial for cell growth through a singular entry and exit point. An integrated electronic system manages flow and pressure, ensuring precise control over environmental conditions. This technology facilitates cell cultivation under conditions closely resembling natural tooth microenvironments, offering opportunities for varied studies from understanding cellular behavior in dental contexts to targeted therapy development. The bioreactor's amalgamation of polymeric components, 3D design, and electronic controls enhances adaptability and accuracy, rendering it a valuable asset in dental research. The report comprehensively delineates the bioreactor's design, operations, and potential applications, showcasing its significant contributions to dental research and regenerative medicine. By amalgamating advanced technologies, this bioreactor emerges as a pivotal tool for investigating cellular processes within dental structures, paving the way for scientific exploration and therapeutic advancements.

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.

Neuropilin-1 (NRP1) is a single transmembrane glycoprotein involved in a variety of physiological events. However, the exact mechanisms by which NRP1 regulates dental pulp stem cells (DPSCs) to differentiate toward an osteo/odontogenic phenotype are poorly understood. Here, we determined the significantly increased expression of full-length NRP1 and glycosaminoglycan (GAG)-modified NRP1 during osteo/odontogenesis in DPSCs. NRP1 was confirmed to promote alkaline phosphatase (ALP) activity, mineralized nodule deposition, protein and mRNA expression of Runx2, DSPP and DMP1 in DPSCs via the loss-of-function and gain-of-function approaches. Further, a non-GAG-modified NRP1 mutant (NRP1 S612A) was generated and the suppression of osteo/odontogenic differentiation was observed in the NRP1 S612A overexpression cells. Knockdown of the adaptor protein shroom3 resulted in the inhibition of osteo/odontogenesis. The protein-protein interaction network, the protein-protein docking and confocal analyses indicated the interactions between NRP1 and shroom3. Furthermore, immunoprecipitation followed by western analysis confirmed the binding of NRP1 to shroom3, but overexpression of NRP1 S612A greatly influenced the recruitment of shroom3 by NRP1. These results provide strong evidence that NRP1 is a critical regulator for osteo/odontogenesis through interacting with shroom3. Moreover, our results indicate that NRP1 S612A attenuates osteo/odontogenesis, suggesting that GAG modification is essential for NRP1 in DPSCs.

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.

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.

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.

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

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.

Mesenchymal stem/stromal cells (MSCs) are multipotent cells located in different areas of the human body. The oral cavity is considered a potential source of MSCs because they have been identified in several dental tissues (D-MSCs). Clinical trials in which cells from these sources were used have shown that they are effective and safe as treatments for tissue regeneration. Importantly, immunoregulatory capacity has been observed in all of these populations; however, this function may vary among the different types of MSCs. Since this property is of clinical interest for cell therapy protocols, it is relevant to analyze the differences in immunoregulatory capacity, as well as the mechanisms used by each type of MSC. Interestingly, D-MSCs are the most suitable source for regenerating mineralized tissues in the oral region. Furthermore, the clinical potential of D-MSCs is supported due to their adequate capacity for proliferation, migration, and differentiation. There is also evidence for their potential application in protocols against autoimmune diseases and other inflammatory conditions due to their immunosuppressive capacity. Therefore, in this review, the immunoregulatory mechanisms identified at the preclinical level in combination with the different types of MSCs found in dental tissues are described, in addition to a description of the clinical trials in which MSCs from these sources have been applied.

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.

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.

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.

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.

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.

A continuing limitation and major challenge in the development and utilization of predictable stem cell therapies (SCTs) is the determination of the optimal dosages of stem cells. Herein, we report the quantification of stem cell fractions (SCF) of human mesenchymal stem cell (MSC) preparations derived from oral tissues. A novel computational methodology, kinetic stem cell (KSC) counting, was used to quantify the SCF and specific cell culture kinetics of stem cells in oral alveolar bone-derived MSC (aBMSCs) from eight patients. These analyses established, for the first time, that the SCF within these heterogeneous, mixed-cell populations differs significantly among donors, ranging from 7% to 77% (ANOVA p < 0.0001). Both the initial SCF of aBMSC preparations and changes in the level of the SCF with serial culture over time showed a high degree of inter-donor variation. Hence, it was revealed that the stability of the SCF of human aBMSC preparations during serial cell culture shows inter-donor variation, with some patient preparations exhibiting sufficient stability to support the long-term net expansion of stem cells. These findings provide important insights for the clinical-scale expansion and biomanufacturing of MSCs, which can facilitate establishing more effective and predictable outcomes in clinical trials and treatments employing SCT.

In regions where preventive dentistry is widespread, tooth loss due to root fracture occurs approximately 10 times more frequently than that due to caries and periodontal disease. Root fracture is most likely to occur in non-vital teeth, where the dental pulp has been removed, often through a procedure known as pulpectomy. However, super minimally invasive pulp (SMIP) therapy has recently been reported as a novel treatment approach for pulpitis of any degree. In this study, SMIP therapy was performed to preserve the vitality of teeth in two patients with severe pulpitis. Case one involved a 35-year-old man with a history of hypertension who presented with intense spontaneous pain in tooth #34. The pain was particularly severe while sleeping at night and on exposure to cold water or heat, but it was absent on percussion. Following the detection of cervical caries and severe pulp exposure, SMIP therapy was administered, and the tooth was subsequently restored using glass ionomer cement. Case two involved an 18-year-old woman with no significant medical history who had deep caries in tooth #46. She experienced mild tooth pain when exposed to cold water, and examination revealed pulp exposure. We applied mineral trioxide aggregate over the dental pulp and restored the tooth using composite resin. The vitality of both teeth was maintained at the three-month follow-up. To our knowledge, this is the first report of SMIP therapy for teeth with severe pulpitis. SMIP therapy is an innovative treatment that may cause a paradigm shift from conventional dental treatment.

For nearly 20 years, dental stem cells (DSCs) have been successfully isolated from mature/immature teeth and surrounding tissue, including dental pulp of permanent teeth and exfoliated deciduous teeth, periodontal ligaments, dental follicles, and gingival and apical papilla. They have several properties (such as self-renewal, multidirectional differentiation, and immunomodulation) and exhibit enormous potential for clinical applications. To date, many clinical articles and clinical trials using DSCs have reported the treatment of pulpitis, periapical lesions, periodontitis, cleft lip and palate, acute ischemic stroke, and so on, and DSC-based therapies obtained satisfactory effects in most clinical trials. In these studies, no adverse events were reported, which suggested the safety of DSC-based therapy. In this review, we outline the characteristics of DSCs and summarize clinical trials and their safety as DSC-based therapies. Meanwhile, we also present the current limitations and perspectives of DSC-based therapy (such as harvesting DSCs from inflamed tissue, applying DSC-conditioned medium/DSC-derived extracellular vesicles, and expanding-free strategies) to provide a theoretical basis for their clinical applications.

Mesenchymal stem/stromal cells (MSCs) are found in almost all postnatal organs. Under appropriate environmental cues, multipotency enables MSCs to serve as progenitors for several lineage-specific, differentiated cell types. In vitro expansion and differentiation of MSCs give the opportunity to obtain hardly available somatic cells, such as neurons. The neurogenic potential of MSCs makes them a promising, autologous source to restore damaged tissue and as such, they have received much attention in the field of regenerative medicine. Several stem cell pool candidates have been studied thus far, but only a few of them showed neurogenic differentiation potential. Due to their embryonic ontology, stem cells residing in the stroma of the dental pulp chamber are an exciting source for in vitro neural cell differentiation. In this study, we review the key properties of dental pulp stem cells (DPSCs), with a particular focus on their neurogenic potential. Moreover, we summarize the various presently available methods used for neural differentiation of human DPSCs also emphasizing the difficulties in reproducibly high production of such cells. We postulate that because DPSCs are stem cells with very close ontology to neurogenic lineages, they may serve as excellent targets for neuronal differentiation in vitro and even for direct reprogramming.