Inflammation–regeneration interplay in the dentine–pulp complex

Systematic assessment of salivary inflammatory markers and dental caries in children: an exploratory study

OBJECTIVE

To investigate associations between a wide panel of salivary inflammatory markers and the presence of dental caries among children.

MATERIAL AND METHODS

In this exploratory, cross-sectional study, 176 children, aged 7-9, underwent a dental examination. Information on the children's oral health habits and lifestyles was collected from their mothers. In addition, saliva samples were collected and analyzed using a multiplex immunoassay. Of 92 inflammatory markers measured, 56 were included in the statistical analyses. To identify potential inflammatory markers associated with caries, we applied low to advanced statistical analyses. First, we performed traditional logistic regression analysis followed by Bonferroni corrections. Thereafter, a more robust and less conservative statistical approach, i.e. Least Absolute Shrinkage and Selection Operator (LASSO), was applied. The models were adjusted for potential confounders.

RESULTS

Of the 176 children in the study, 22.2% were affected by caries. Among the 56 salivary inflammatory markers, only macrophage colony-stimulating factor 1 (CSF1) was selected by the LASSO and found to be positively associated with the presence of caries.

CONCLUSIONS

The observed association between CSF1 and the presence of caries may be of clinical value in caries risk management and early diagnosis. Larger studies are warranted to assess the replicability of our findings.

Effects of aging and inflammation on catalase activity in human dental pulp

OBJECTIVES

In this study, it was aimed to examine the catalase activity in clinically healthy and caries-related inflamed symptomatic human dental pulps of young and old individuals.

DESIGN

Sixty pulp samples from young and old healthy donors, were collected depending on pulpal status. 48 samples were used for spectrophotometric analysis and 12 samples for immunohistochemistry. Healthy pulps were maintained from non-carries, extracted third molars. Reversible and irreversible pulpitis samples were obtained by pulp extirpation during endodontic treatment. Following homogenization catalase enzyme activity was determined by spectrophotometry. Additionally, two pulp tissue samples from each group were fixed and evaluated for catalase immunoreactivity.

RESULTS

Catalase enzyme activity in old healthy pulp samples were significantly higher than healthy young samples (p ≤ 0.05). Reversible and irreversible pulpitis samples indicated significantly decreased activity compared to healthy samples in elderly group (p ≤ 0.05). Young reversible pulpitis samples showed significantly increased catalase activity when compared to irreversible pulpitis and the reversible pulpitis samples in elderly group (p ≤ 0.05). Immunohistochemical evaluation indicated that there was intense catalase immunoreactivity in young patients with reversible pulpitis compared with reversible pulpitis in elderly group. However, weak immunoreactivity was observed in young irreversible pulpitis and elderly reversible pulpitis samples.

CONCLUSIONS

The pulp tissues presented different levels of catalase activities against pulpitis and aging.

The Influence of New Bioactive Materials on Pulp–Dentin Complex Regeneration in the Assessment of Cone Bone Computed Tomography (CBCT) and Computed Micro-Tomography (Micro-CT) from a Present and Future Perspective—A Systematic Review

The present paper is the first article providing a systematic literature review on the visualization of tertiary dentin influenced by modern bioactive materials in CBCT and micro-CT. Six database searches of studies on tertiary dentin visualization using CBCT produced 622 records in total, and the search of the studies on tertiary dentin using micro-CT produced 502 records in total. The results were thoroughly selected considering the inclusion criteria, and five research papers using CBCT and nine research papers using micro-CT for visualization of tertiary dentin were eventually qualified for the analysis. All the non-randomized and randomized studies presented good and high levels of quality evidence, respectively. Among the bioactive materials used, the most frequently analysed were: MTA, Biodentine dentin matrix hydrogel, Pro Root MTA, and EndoSequence root repair material. The highest thickness of the tertiary dentin was achieved after the use of MTA material in both imaging techniques. The remaining parameters had different results, taking into account the CBCT and micro-CT analysis. The possibilities of the qualitative and quantitative assessment of the particular parameters of tertiary dentin using CBCT and micro-CT techniques were presented and analysed. CBCT and micro-CT analyses can be useful in the assessment of tertiary dentin formed beneath the bioactive material applied during vital pulp treatment. The research argues that the presented results differ depending on the material applied to the pulp, the study duration (4–6 weeks), difference in teeth, species (rats, human), as well as the applied technique and differences in computer software used for the analysis.

Preclinical 3D-printed laboratory simulation of deep caries and the exposed pulp reduced student anxiety and stress, while increasing confidence and knowledge in vital pulp treatment

Aim

To evaluate the impact of a preclinical laboratory session using 3D printed teeth on dental student stress, anxiety, confidence and knowledge when treating deep caries and pulp exposure.

Methodology

This was a two‐centre controlled study, with randomized distribution of students into two groups: a vital pulp treatment (VPT) lecture‐only (control) group and a VPT‐lecture combined with a VPT‐laboratory (experimental) group. In both universities, preclinical students with endodontic or operative dentistry laboratory sessions could participate. All students were invited to the lecture. Two weeks later (timepoint‐T1), both groups completed validated and bespoke questionnaires and scales to evaluate their stress (Stress‐VAS), anxiety (STAI Trait [T] and State [S]), self‐confidence and knowledge. Thereafter, only the experimental group attended the hands‐on laboratory session demonstrating the techniques of selective caries removal and partial pulpotomy on a commercial 3D‐printed tooth. Two weeks later (timepoint‐T2), the participants from both groups repopulated the same questionnaires and VAS. The control group had the laboratory session after the completion of the study. The statistical analysis was performed with Statistica® (significance p = .05). The homogeneity between the two samples was checked by Khi² and Student tests. Stress‐VAS, STAI‐S, confidence and knowledge scores were compared within each group, and between the two groups, at T1 and T2, with a repeated measures anova test (+/−Tukey post‐hoc test).

Results

The groups comprised 54 students each, with no statistical difference between the groups regarding demographic, academic data and STAI‐T score. The two groups had no significant difference of Stress‐VAS, STAI‐S, confidence and knowledge scores at T1 while they presented a significant difference in stress, anxiety and confidence scores at T2, but with no significant difference in knowledge score. However, knowledge score, as other parameters, improved significantly between T1 and T2 in the experimental group.

Conclusions

The addition of a laboratory session using 3D‐printed teeth that simulated deep caries and pulp exposure management, significantly reduced the stress and anxiety of students and increased their confidence. Within the limitations of this study, the benefit of introducing new technology in increasing student confidence and reducing stress offers opportunity for educational improvement in the VPT and cariology areas.

Sphingosine-1-phosphate hinders the osteogenic differentiation of dental pulp stem cells in association with AKT signaling pathways

Sphingosine-1-phosphate (S1P) is an important lipid mediator that regulates a diverse range of intracellular cell signaling pathways that are relevant to tissue engineering and regenerative medicine. However, the precise function of S1P in dental pulp stem cells (DPSCs) and its osteogenic differentiation remains unclear. We here investigated the function of S1P/S1P receptor (S1PR)-mediated cellular signaling in the osteogenic differentiation of DPSCs and clarified the fundamental signaling pathway. Our results showed that S1P-treated DPSCs exhibited a low rate of differentiation toward the osteogenic phenotype in association with a marked reduction in osteogenesis-related gene expression and AKT activation. Of note, both S1PR1/S1PR3 and S1PR2 agonists significantly downregulated the expression of osteogenic genes and suppressed AKT activation, resulting in an attenuated osteogenic capacity of DPSCs. Most importantly, an AKT activator completely abrogated the S1P-mediated downregulation of osteoblastic markers and partially prevented S1P-mediated attenuation effects during osteogenesis. Intriguingly, the pro-inflammatory TNF-α cytokine promoted the infiltration of macrophages toward DPSCs and induced S1P production in both DPSCs and macrophages. Our findings indicate that the elevation of S1P under inflammatory conditions suppresses the osteogenic capacity of the DPSCs responsible for regenerative endodontics.

Minimal Intervention Dentistry: Biocompatibility and Mechanism of Action of Products for Chemical-Mechanical Removal of Carious Tissue

Conventional method for removal of carious tissue using low speed drills usually induce noise and vibration, in addition to thermal and pressure effects that can be harmful to the pulp tissue and cause fear in children. Therefore, several alternative methods are being developed to try to minimize the unpleasant perception of the patient during caries removal. Chemical-mechanical removal of carious tissue goal is to selectively remove the carious lesion, which reduces the amount of bacteria inside the cavity without removing the tissue susceptible to remineralization. This method is also able to minimize the tactile perception by the patient during the manipulation of the lesion compared to the conventional method, and, therefore, it has been widely accepted among phobic patients, children and special needs patients. Due to the close relationship between dentin and pulp tissue, all injuries imposed on this dentin may have repercussions on the underlying pulp connective tissue. The morphological aspects of remaining dentin favor the diffusion of chemical components of dental materials, which can be toxic to the pulp tissue or even negatively interfere in the reparative process. Thus, considering the proximity between the applied material and the underlying pulp tissue, especially in deep cavities, there is a need to assess the biological behavior of dental materials against pulp cells, since aggressions to the pulp tissue can be caused not only by metabolites from microorganisms involved in dental caries but also by components that are released from these products. This subject was explored in this narrative literature review.

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

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

Pathophysiology of Demineralization, Part I: Attrition, Erosion, Abfraction, and Noncarious Cervical Lesions

PURPOSE OF THE REVIEW

Compare pathophysiology for infectious and noninfectious demineralization disease relative to mineral maintenance, physiologic fluoride levels, and mechanical degradation.

RECENT FINDINGS

Environmental acidity, biomechanics, and intercrystalline percolation of endemic fluoride regulate resistance to demineralization relative to osteopenia, noncarious cervical lesions, and dental caries. Demineralization is the most prevalent chronic disease in the world: osteoporosis (OP) >10%, dental caries ~100%. OP is severely debilitating while caries is potentially fatal. Mineralized tissues have a common physiology: cell-mediated apposition, protein matrix, fluid logistics (blood, saliva), intercrystalline ion percolation, cyclic demineralization/remineralization, and acid-based degradation (microbes, clastic cells). Etiology of demineralization involves fluid percolation, metabolism, homeostasis, biomechanics, mechanical wear (attrition or abrasion), and biofilm-related infections. Bone mineral density measurement assesses skeletal mass. Attrition, abrasion, erosion, and abfraction are diagnosed visually, but invisible subsurface caries <400μm cannot be detected. Controlling demineralization at all levels is an important horizon for cost-effective wellness worldwide.

A critical review of in vitro research methodologies used to study mineralization in human dental pulp cell cultures

Background

The pulp contains a resident population of stem cells which can be stimulated to differentiate in order to repair the tooth by generating a mineralized extracellular matrix. Over recent decades there has been considerable interest in utilizing in vitro cell culture models to study dentinogenesis, with the aim of developing regenerative endodontic procedures, particularly where some vital pulp tissue remains.

Objectives

The purpose of this review is to provide a structured oversight of in vitro research methodologies which have been used to study human pulp mineralization processes.

Method

The literature was screened in the PubMed database up to March 2021 to identify manuscripts reporting the use of human dental pulp cells to study mineralization. The dataset identified 343 publications initially which were further screened and consequently 166 studies were identified and it was methodologically mined for information on: i) study purpose, ii) source and characterization of cells, iii) mineralizing supplements and concentrations, and iv) assays and markers used to characterize mineralization and differentiation, and the data was used to write this narrative review.

Results

Most published studies aimed at characterizing new biological stimulants for mineralization as well as determining the effect of scaffolds and dental (bio)materials. In general, pulp cells were isolated by enzymatic digestion, although the pulp explant technique was also common. For enzymatic digestion, a range of enzymes and concentrations were utilized, although collagenase type I and dispase were the most frequent. Isolated cells were not routinely characterized using either fluorescence‐activated cell sorting (FACS) and magnetic‐activated cell sorting (MACS) approaches and there was little consistency in terming cultures as dental pulp cells or dental pulp stem cells. A combination of media supplements, at a range of concentrations, of dexamethasone, ascorbic acid and beta‐glycerophosphate, were frequently applied as the basis for the experimental conditions. Alizarin Red S (ARS) staining was the method of choice for assessment of mineralization at 21‐days. Alkaline phosphatase assay was relatively frequently applied, solely or in combination with ARS staining. Further assessment of differentiation status was performed using transcript or protein markers, with dentine sialophosphoprotein (DSPP), osteocalcin and dentine matrix protein‐1 (DMP ‐1), the most frequent.

Discussion

While this review highlights variability among experimental approaches, it does however identify a consensus experimental approach.

Conclusion

Standardization of experimental conditions and sustained research will significantly benefit endodontic patient outcomes in the future.

Evaluation of a Hypersensitivity Inhibitor Containing a Novel Monomer That Induces Remineralization-A Case Series in Pediatric Patients

BACKGROUND

Recently, tooth deformities have been frequently encountered by pediatric dentists. Severe enamel hypomineralization sometimes induces pain such as hyperesthesia, but composite resin restoration is difficult because it often detaches without any cavity preparation. Resin-based hypersensitivity inhibitors for tooth physically seal the dentinal tubules. It was reported that hypersensitivity inhibitor containing novel adhesive monomers forms apatite and induces remineralization in vitro. Therefore, these case series assessed the clinical effects of remineralization and the suppression of hypersensitivity by Bio Coat Ca (Sun Medical, Shiga, Japan).

METHODS

After mechanical tooth cleaning was performed, the hypersensitivity inhibitors were applied and cured by light exposure. Changes in hypersensitivity were determined by visual analog scale (VAS). The improvement of hypomineralization was evaluated by the change in color tone based on the digital images of intraoral photographs.

RESULTS

After repeated monthly treatments, these cases showed decreased hypersensitivity after the fourth application, while the opaque white and brownish color improved on the seventh application.

CONCLUSION

This novel hypersensitivity inhibitor with calcium salt of 4-methacryloxyethyl trimellitic acid (C-MET) and 10-methacryloyloxydecyl dihydrogen calcium phosphate (MDCP) not only suppressed hypersensitivity but also improved cloudiness and brown spots in recently erupted permanent teeth in presented cases.

Pulp capping with mineral trioxide aggregate or Biodentine: a comparison of mineralized barrier formation and inflammatory and degenerative events

Biodentine in endodontic practice has been widely investigated, but comprehensive histological descriptions of degenerative and inflammatory responses are not covered in most of the studies that compare pulp capping materials. This study aimed to evaluate pulpal responses to mineral trioxide aggregate (MTA Angelus) and Biodentine, focusing on mineralized barrier formation and on inflammatory and degenerative events. 80 male Wistar rats were assigned to 5 groups, according to the materials used for pulp capping and coronal sealing (n=8 per group/period). The lower first molars were mechanically exposed, capped with either MTA or Biodentine, and restored with silver amalgam. In an additional test group, the teeth were capped and sealed with Biodentine. The teeth capped with gutta-percha and restored with silver amalgam served as positive control, whereas untreated teeth served as negative control. Pulpal responses and coronal sealing were evaluated after 14 or 21 days. Data was statistically analyzed by the Kruskal-Wallis and Dunn's post hoc tests (p<0.05). Biodentine and MTA presented satisfactory results, showing a milder inflammatory response (p<0.0001) and more pronounced formation of mineralized barrier (p<0.0001) compared to the teeth capped with gutta-percha. As a restorative material, Biodentine kept coronal sealing in only 37.5% of the samples. Biodentine showed favorable properties in vital pulp therapy, being similar to MTA. However, it was not effective in protecting dental pulp from microleakage during the experimental period.

Effect of silicon-doped calcium phosphate cement on angiogenesis based on controlled macrophage polarization

Vascularization is an important early indicator of osteogenesis involving biomaterials. Bone repair and new bone formation are associated with extensive neovascularization. Silicon-based biomaterials have attracted widespread attention due to their rapid vascularization. Although calcium phosphate cement (CPC) is a mature substitute for bone, the application of CPC is limited by its slow degradation and insufficient promotion of neovascularization. Calcium silicate (CS) has been shown to stimulate vascular endothelial proliferation. Thus, CS may be added to CPC (CPC-CS) to improve the biocompatibility and neovascularization of CPC. In the early phase of bone repair (the inflammatory phase), macrophages accumulate around the biomaterial and exert both anti- and pro-inflammatory effects. However, the effect of CPC-CS on macrophage polarization is not known, and it is not clear whether the effect on neovascularization is mediated through macrophage polarization. In the present study, we explored whether silicon-mediated macrophage polarization contributes to vascularization by evaluating the CPC-CS-mediated changes in the immuno-environment under different silicate ion contents both in vivo and in vitro. We found that the silicon released from CPC-CS can promote macrophage polarization into the M2 phenotype and rapid endothelial neovascularization during bone repair. Dramatic neovascularization and osteogenesis were observed in mouse calvarial bone defects implanted with CPC-CS containing 60% CS. These findings suggest that CPC-CS is a novel biomaterial that can modulate immune response, promote endothelial proliferation, and facilitate neovascularization and osteogenesis. Thus, CPC-CS shows potential as a bone substitute material.

Oral Cavity as a Source of Mesenchymal Stem Cells Useful for Regenerative Medicine in Dentistry

The use of mesenchymal stem cells (MSCs) for regenerative purposes has become common in a large variety of diseases. In the dental and maxillofacial field, there are emerging clinical needs that could benefit from MSC-based therapeutic approaches. Even though MSCs can be isolated from different tissues, such as bone marrow, adipose tissue, etc., and are known for their multilineage differentiation, their different anatomical origin can affect the capability to differentiate into a specific tissue. For instance, MSCs isolated from the oral cavity might be more effective than adipose-derived stem cells (ASCs) for the treatment of dental defects. Indeed, in the oral cavity, there are different sources of MSCs that have been individually proposed as promising candidates for tissue engineering protocols. The therapeutic strategy based on MSCs can be direct, by using cells as components of the tissue to be regenerated, or indirect, aimed at delivering local growth factors, cytokines, and chemokines produced by the MSCs. Here, the authors outline the major sources of mesenchymal stem cells attainable from the oral cavity and discuss their possible usage in some of the most compelling therapeutic frontiers, such as periodontal disease and dental pulp regeneration.

Nell-1 attenuates lipopolysaccharide-induced inflammation in human dental pulp cells

Nel-like molecule type 1 (Nell-1) is a secreted protein that plays an important role in osteoinduction in multiple animal models. A previous study has suggested the anti-inflammatory effect of Nell-1 on bone inflammation inhibition. However, its role in pulpitis has not been investigated. The present study aims to explore the effect of human recombinant Nell-1 (Nell-1) on rat pulp inflammation response, and its effect on lipopolysaccharide-induced inflammation in human dental pulp cells and its related intracellular signaling pathways. 30 Wistar rats with healthy non-carious maxillary first molars were chosen, Nell-1 was absorbed onto a sterile collagen sponge and capped onto exposed pulps. The expression of IL-6 and IL-8 were detected by immunohistochemical staining. Human dental pulp cells (hDPCs) were isolated from healthy extracted premolars and third molars. hDPCs were co-cultured with Escherichia coli lipopolysaccharide (LPS), Nell-1 protein, and mitogen-activated protein kinase (MAPK) inhibitors. The expression of pro-inflammatory cytokines and chemokines, such as IL-6 and IL-8, was examined via quantitative real-time PCR and enzyme-linked immunosorbent assay. The results showed that Nell-1 inhibited the inflammatory response of rat pulp. LPS treatment contributed to the expression of inflammatory factors in hDPCs, whereas Nell-1 obviously suppressed the LPS-induced inflammation. p38 MAPK and extracellular signal-regulated kinase (ERK) MAPK inhibitors attenuated the anti-inflammatory effect of hrNell-1, whereas the c-Jun N-terminal kinases (JNK) MAPK inhibitor exerted minimal effect. Therefore Nell-1 could inhibit LPS-induced inflammation in human dental pulp cells, and this effect may be mediated by p38 and ERK MAPK signaling pathways, but not JNK MAPK signaling pathway.

Synthesis, characterization, and evaluation of curcumin-loaded endodontic reparative material

Curcumin (CUR) is an ancient therapeutic agent with remarkable antimicrobial and anti-inflammatory properties. The purpose of the current study was to synthesize and evaluate a curcumin-based reparative endodontic material to reduce infection and inflammation besides the induction of mineralization during the healing of the dentin-pulp complex. Poly-ɛ-caprolactone (PCL)/gelatin (Gel)/CUR scaffold was synthesized and assessed by scanning electron microscopy, Fourier transform infrared spectroscopy, and thermo-gravimetric analysis (TGA). Agar diffusion test was performed against E. coli, A. baumannii, P. aeruginosa, S. aureus, E. faecalis, and S. mutans. Moreover, proliferative, antioxidative, anti-inflammatory, and calcification properties of these scaffolds on human dental pulp stem cells (hDPSCs) were evaluated. The results showed that PCL/Gel/CUR scaffold had antibacterial effects. Also, these CUR-based scaffolds had significant inhibitory effects on the expression of tumor necrosis factor α and DCF from inflamed hDPSCs (p < 0.05). Moreover, the induction of mineralization in hDPSCs significantly increased after seeding on CUR-based scaffolds (p < 0.05). Based on these findings, the investigated CUR-loaded material was fabricated successfully and provided an appropriate structure for the attachment and proliferation of hDPSCs. It was found that these scaffolds had antimicrobial, antioxidant, and anti-inflammatory characteristics and could induce mineralization in hDPSCs, which is essential for healing and repairing the injured dentin-pulp complex.

Exploiting dentine matrix proteins in cell-free approaches for periradicular tissue engineering

The recent discovery of mesenchymal stem cells within periapical lesions (PL-MSC) has presented novel opportunities for managing periradicular diseases in adult teeth by way of enhancing tissue regeneration. This discovery coincides with the current paradigm shift toward biologically driven treatment strategies in endodontics, which have typically been reserved for non-vital immature permanent teeth. One such approach that shows promise is utilizing local endogenous non-collagenous dentine extracellular matrix components (dECM) to recruit and upregulate the intrinsic regenerative capacity of PL-MSCs in situ. At picogram levels, these morphogens have demonstrated tremendous ability to enhance the cellular activities in in vitro and in vivo animal studies that would otherwise be necessary for periradicular regeneration. Briefly, these include proliferation, viability, migration, differentiation, and mineralization. Therefore, topical application of dECMs during ortho- or retrograde root canal treatment could potentially enhance and sustain the regenerative mechanisms within diseased periapical tissues that are responsible for attaining favorable clinical and radiographic outcomes. This would provide many advantages when compared with conventional antimicrobial-only therapies for apical periodontitis (AP), which do not directly stimulate healing and have had stagnant success rates over the past five decades despite significant advances in operative techniques. The aim of this narrative review was to present the novel concept of exploiting endogenous dECMs as clinical tools for treating AP in mature permanent teeth. A large scope of literature was summarized to discuss the issues associated with conventional treatment modalities; current knowledge surrounding PL-MSCs; composition of the dECM; inductive potentials of dECM morphogens in other odontogenic stem cell niches; how treatment protocols can be adapted to take advantage of dECMs and PL-MSCs; and finally, the challenges currently impeding successful clinical translation alongside directions for future research.

The Regenerative Potential of bFGF in Dental Pulp Repair and Regeneration

Regenerative endodontic therapy intends to induce the host’s natural wound-healing process, which can restore the vitality, immunity, and sensitivity of the inflammatory or necrotic pulp tissue destroyed by infection or trauma. Myriads of growth factors are critical in the processes of pulp repair and regeneration. Among the key regulatory factors are the fibroblast growth factors, which have turned out to be the master regulators of both organogenesis and tissue homeostasis. Fibroblast growth factors, a family composed of 22 polypeptides, have been used in tissue repair and regeneration settings, in conditions as diverse as burns, ulcers, bone-related diseases, and spinal cord injuries. Meanwhile, in dentistry, the basic fibroblast growth factor is the most frequently investigated. Thereby, the aim of this review is 2-fold: 1) foremost, to explore the underlying mechanisms of the bFGF in dental pulp repair and regeneration and 2) in addition, to shed light on the potential therapeutic strategies of the bFGF in dental pulp–related clinical applications.

Evaluation of Pulp Repair after BiodentineTM Full Pulpotomy in a Rat Molar Model of Pulpitis

Dental pulp is a dynamic tissue able to heal after injury under moderate inflammatory conditions. Our study aimed to evaluate pulp repair under inflammatory conditions in rats. For this purpose, we developed a rat model of controlled pulpitis followed by pulpotomy with a tricalcium silicate-based cement. Fifty-four cavities were prepared on the occlusal face of the maxillary upper first molar of 27 eight-week-old male rats. E. coli lipopolysaccharides at 10 mg/mL or phosphate-buffered saline PBS was injected after pulp injury. Non-inflamed molars were used as controls. Levels of inflammation-related molecules were measured 6 and 24 h after induction by enzyme-linked immunosorbent assay of coronal pulp samples. Pulp capping and coronal obturation after pulpotomy were performed with tricalcium silicate-based cement. Four and fifteen days after pulpotomy, histological and immunohistochemical analysis was performed to assess pulp inflammation and repair processes. Our results showed significantly higher levels of innate inflammatory proteins (IL-1β, IL-6, TNF-α and CXCL-1) compared with those in controls. Moderate residual inflammation near the capping material was demonstrated by histology and immunohistochemistry, with the presence of few CD68-positive cells. We showed that, in this model of controlled pulpitis, pulpotomy with Biodentine^TM allowed the synthesis at the injury site of a mineralized bridge formed from mineralized tissue secreted by cells displaying odontoblastic characteristics. Analysis of these data suggests overall that, with the limitations inherent to findings in animal models, pulpotomy with a silicate-based cement is a good treatment for controlling inflammation and enhancing repair in cases of controlled pulpitis.

Odontoblast markers and dentine reactions in carious primary molars with and without hypomineralised enamel defects

BACKGROUND

Wnt/β-Catenin signalling and DMP1 have key roles in tertiary dentinogenesis.

AIM

To compare the relationship between remaining dentine thickness (RDT), tertiary dentine thickness (TDT), β-catenin and dentine matrix protein 1 (DMP1) in carious second primary molar teeth with normal (SPM) and hypomineralised enamel (HSPM).

DESIGN

Extracted carious SPM and HSPM were fixed, sectioned (5 μm) and stained with haematoxylin and eosin or with indirect immunofluorescence for β-catenin and DMP1. Image analysis was performed to determine RDT, TDT, β-catenin and DMP1 intensity in the odontoblast layer and dentine-pulp complex.

RESULTS

Carious SPM (n = 11; mean RDT = 1536.1 μm) and HSPM (n = 12; mean RDT = 1179.9 μm) had mean TDT 248.6 μm and 518.1 μm, respectively (P = .02). There were no significant differences in intensity values in the odontoblast layer and dentine-pulp complex for β-catenin and DMP1 for both groups.

CONCLUSION

There was no observable variation in Wnt/β-catenin and DMP1 expression between HSPM and SPM despite a statistically significant twofold increased TDT in HSPM compared with SPM that had similar RDT. Thus, the observed increased TDT in HSPM is more likely due to an earlier onset of repair processes rather than an amplified response to caries.

Fibroblasts Control Macrophage Differentiation during Pulp Inflammation

INTRODUCTION

During pulp inflammation, recruited macrophages can differentiate into 2 phenotypes: proinflammatory M1 and anti-inflammatory M2. Pulp fibroblasts have previously been shown to regulate pulp inflammation via cytokine and growth factor secretion. We hypothesized that upon carious injury, pulp fibroblasts interact with macrophages and modulate their differentiation.

METHODS

Cultures of pulp fibroblasts were physically injured and incubated with lipoteichoic acid (LTA) to mimic the pulp environment underlying a carious lesion. Physical injuries without LTA were performed on cultured fibroblasts to simulate the surrounding pulp tissue. Fibroblast supernatants were collected and added to undifferentiated macrophages to study their differentiation into M1 or M2 phenotypes by investigating cytokine secretion profiles and phagocytosis capacity. Histologic staining and immunofluorescence were performed on healthy and carious human tooth sections to localize the 2 macrophage phenotypes.

RESULTS

LTA-stimulated fibroblasts induced macrophage differentiation into the M1 phenotype with a significant increase both in tumor necrosis factor alpha secretion and phagocytosis capacity. By contrast, injured fibroblasts without LTA led to M2 differentiation with a significant increase in interleukin 10 secretion and low phagocytosis capacity. In carious teeth, M1 macrophages were detected mainly in the pulp zone underlying caries, whereas M2 macrophages were detected in the peripheral inflammatory zone.

CONCLUSIONS

Fibroblasts induced macrophage differentiation to proinflammatory M1 with high bacteria phagocytosis capacity to control infection at the carious front. Fibroblasts located at the periphery of the inflammatory zone induced macrophage differentiation to anti-inflammatory M2. The fine balance between the 2 phenotypes may represent a prerequisite for initiating the healing process.

BiodentineTM Full Pulpotomy in Mature Permanent Teeth with Irreversible Pulpitis and Apical Periodontitis

Vital pulp therapy, including direct pulp capping and partial and full pulpotomy, is primarily indicated for immature or mature permanent teeth with reversible pulpitis. Mature permanent teeth with irreversible pulpitis are frequently treated with root canal therapy. This report presents two cases of full pulpotomy using BiodentineTM in mature permanent teeth with irreversible pulpitis and acute apical periodontitis. The periapical radiograph illustrated a deep carious lesion extended to the pulp with apical radiolucency lesion or widened periodontal ligament space. Full pulpotomy with a tricalcium silicate-based cement was chosen as the definitive treatment. After decayed tissue excavation under a rubber dam, the exposed pulp tissue was amputated to the level of the canal orifice with a new sterile bur. BiodentineTM was applied as the pulp capping agent after hemostasis was obtained and for temporary restoration. The clinical signs disappeared quickly after the treatment. After one month, the coronal part of the temporary restoration was removed, and a composite resin was placed over the capping agent as a final restoration. At two-year follow-ups, the teeth were asymptomatic. Radiographs showed healing of the periapical lesion and periodontal ligament. BiodentineTM full pulpotomy of mature permanent teeth with irreversible pulpitis and apical periodontitis can be an alternative option to root canal therapy.

Reducing Intervention in the COVID-19 Era: Opportunities for Vital Pulp Treatment

Over the last 12 months, the Severe Acute Respiratory Syndrome Coronavirus 2 (SARS-COV-2) virus has emerged as a significant global health problem with extensive repercussions for the practise of dentistry. As the principle transmission-route is via droplet-spread, aerosol-generating dental procedures (AGPs) present an exquisite challenge, which either has to be avoided or performed using strict infection-control measures, which increase the deployment of resources and cost. This new working environment necessitates the adoption of simplified, yet effective procedures that reduce intervention and minimise clinical chair time to short, single visits. Vital pulp treatment (VPT) has emerged as an attractive, technically less-complicated group of biologically-based management strategies that are aimed at maintaining pulp vitality and avoiding root canal treatment (RCT). These procedures are carried out in a strict aseptic environment using a rubber dam and have a reported high success rate, suggesting that they could be considered as effective and simple alternative therapies to relieve pain and avoid multiple visit RCT and other endodontic procedures. The relevance of promoting a simple, predictable and effective alternative to traditional, more complex dentistry has never been more compelling. In this perspective article, the latest advances in VPT are highlighted, along with an analysis of their relative success and compelling reasons why we as dentists should be adopting these treatment approaches. Thereafter, case selection, prognostic factors, techniques, limitations and future prospects of these procedures are discussed.

Biomaterial and Biofilm Interactions with the Pulp-Dentin Complex-on-a-Chip

Calcium silicate cements (CSCs) are the choice materials for vital pulp therapy because of their bioactive properties, promotion of pulp repair, and dentin bridge formation. Despite the significant progress made in understanding CSCs' mechanisms of action, the key events that characterize the early interplay between CSC-dentin-pulp are still poorly understood. To address this gap, a microfluidic device, the "tooth-on-a-chip," which was developed to emulate the biomaterial-dentin-pulp interface, was used to test 1) the effect of CSCs (ProRoot, Biodentine, and TheraCal) on the viability and proliferation of human dental pulp stem cells, 2) variations of pH, and 3) release within the pulp chamber of transforming growth factor-β (TGFβ) as a surrogate of the bioactive dentin matrix molecules. ProRoot significantly increased the extraction of TGFβ (P < 0.05) within 24 to 72 h and, along with Biodentine, induced higher cell proliferation (P > 0.05), while TheraCal decreased cell viability and provoked atypical changes in cell morphology. No correlation between TGFβ levels and pH was observed. Further, we established a biofilm of Streptococcus mutans on-chip to model the biomaterial-biofilm-dentin interface and conducted a live and dead assay to test the antimicrobial capability of ProRoot in real time. In conclusion, the device allows for direct characterization of the interaction of bioactive dental materials with the dentin-pulp complex on a model of restored tooth while enabling assessment of antibiofilm properties at the interface in real time that was previously unattainable.

Specialized pro-resolving lipid mediators in endodontics: a narrative review

Endodontics is the branch of dentistry concerned with the morphology, physiology, and pathology of the human dental pulp and periradicular tissues. Human dental pulp is a highly dynamic tissue equipped with a network of resident immunocompetent cells that play major roles in the defense against pathogens and during tissue injury. However, the efficiency of these mechanisms during dental pulp inflammation (pulpitis) varies due to anatomical and physiological restrictions. Uncontrolled, excessive, or unresolved inflammation can lead to pulp tissue necrosis and subsequent bone infections called apical periodontitis. In most cases, pulpitis treatment consists of total pulp removal. Although this strategy has a good success rate, this treatment has some drawbacks (lack of defense mechanisms, loss of healing capacities, incomplete formation of the root in young patients). In a sizeable number of clinical situations, the decision to perform pulp extirpation and endodontic treatment is justifiable by the lack of therapeutic tools that could otherwise limit the immune/inflammatory process. In the past few decades, many studies have demonstrated that the resolution of acute inflammation is necessary to avoid the development of chronic inflammation and to promote repair or regeneration. This active process is orchestrated by Specialized Pro-resolving lipid Mediators (SPMs), including lipoxins, resolvins, protectins and maresins. Interestingly, SPMs do not have direct anti-inflammatory effects by inhibiting or directly blocking this process but can actively reduce neutrophil infiltration into inflamed tissues, enhance efferocytosis and bacterial phagocytosis by monocytes and macrophages and simultaneously inhibit inflammatory cytokine production. Experimental clinical application of SPMs has shown promising result in a wide range of inflammatory diseases, such as renal fibrosis, cerebral ischemia, marginal periodontitis, and cancer; the potential of SPMs in endodontic therapy has recently been explored. In this review, our objective was to analyze the involvement and potential use of SPMs in endodontic therapies with an emphasis on SPM delivery systems to effectively administer SPMs into the dental pulp space.

Roles of Dental Mesenchymal Stem Cells in the Management of Immature Necrotic Permanent Teeth

Dental caries and trauma always lead to pulp necrosis and subsequent root development arrest of young permanent teeth. The traditional treatment, apexification, with the absence of further root formation, results in abnormal root morphology and compromises long-term prognosis. Regeneration endodontics procedures (REPs) have been developed and considered as an alternative strategy for management of immature permanent teeth with pulpal necrosis, including cell-free and cell-based REPs. Cell-free REPs, including revascularization and cell homing with molecules recruiting endogenous mesenchymal stem cells (MSCs), have been widely applied in clinical treatment, showing optimistic periapical lesion healing and continued root development. However, the regenerated pulp-dentin complex is still absent in these cases. Dental MSCs, as one of the essentials of tissue engineering, are vital seed cells in regenerative medicine. Dental MSC-based REPs have presented promising potential with pulp-dentin regeneration in large animal studies and clinical trials via cell transplantation. In the present review, we summarize current understanding of the biological basis of clinical treatments for immature necrotic permanent teeth and the roles of dental MSCs during this process and update the progress of MSC-based REPs in the administration of immature necrotic permanent teeth.

Review of Animal Models to Study Pulp Inflammation

Human dental pulp is a highly dynamic tissue equipped with a network of resident immunocompetent cells that play a major role in the defense against pathogens and during tissue injury. Animal studies are mandatory and complementary to in vitro experiments when studying the physiopathology of dental pulp, new diagnostic tools, or innovative therapeutic strategies. This animal approach makes it possible to define a benefit-risk ratio necessary to be subsequently tested in humans. Among the animal kingdom, rodents, rabbits, ferrets, swine, dogs, and non-human primates have been used to model human pulpitis. The diversity of animals found in studies indicate the difficulty of choosing the correct and most efficient model. Each animal model has its own characteristics that may be advantageous or limiting, according to the studied parameters. These elements have to be considered in preclinical studies. This article aims to provide a thorough understanding of the different animal models used to study pulp inflammation. This may help to find the most pertinent or appropriate animal model depending on the hypothesis investigated and the expected results.

Histology of human teeth: Standard and specific staining methods revisited

OBJECTIVE

Histological techniques have long been an integral part of dental research. Especially the processing of complex tissues poses specific challenges, however, literature offers only few technical references. Objectives of this study were therefore to optimize histological staining methods and compile detailed protocols for preparation and staining of dental tissues.

METHODS

Human teeth were collected and fixed with 4 % formaldehyde solution after extraction. Subsequently, teeth were decalcified in 17 % EDTA or Morse's solution over a period of 28 days. The extent of decalcification was determined by weight loss and radiography. After sectioning, histological staining methods were optimized for their use on teeth. These included hematoxylin-eosin, Masson trichrome, Masson-Goldner trichrome and May-Gruenwald-Giemsa staining. Nerve fibres were visualized by luxol fast blue staining and Bodian silver staining. In addition, specific methods like TRAP, modified Brown and Brenn as well as picrosirius red staining with light polarization or fluorescence were applied and optimized.

RESULTS

Preparation of an artificial access to the pulp chamber was essential to ensure prompt penetration of the chemicals. Decalcification with Morse's solution took at least two weeks but was more efficient than 17 % ETDA, where thorough demineralization was achieved only after three weeks. The staining methods exhibited differences not only regarding their ability to display specific structures of interest, but also in terms of reproducibility.

CONCLUSION

High-quality histology of teeth can only be achieved after optimal tissue preparation and accurate staining. A complementary use of staining techniques is necessary to answer specific research questions.

Potential application of immunotherapy for modulation of pulp inflammation: opportunities for vital pulp treatment

Caries results in the demineralization and destruction of enamel and dentine, and as the disease progresses, irreversible pulpitis can occur. Vital pulp therapy (VPT) is directed towards pulp preservation and the prevention of the progression of inflammation. The outcomes of VPT are not always predictable, and there is often a poor correlation between clinical signs and symptoms, and the events occurring at a molecular level. The inflamed pulp expresses increased levels of cytokines, including tumour necrosis factor (TNF)-α, interleukin (IL)-1α, IL-1β, IL-4, IL-6, IL-8, IL-17 and IL-23, which recruit and drive a complex cellular immune response. Chronic inflammation and sustained cytokine release can result in irreversible pulp damage and a decreased capacity for tissue healing. Other chronic inflammatory diseases, such as psoriasis, inflammatory bowel diseases and rheumatoid arthritis, are also characterized by an dysregulated immune response composed of relatively high cytokine levels and increased numbers of immune cells along with microbial and hard-soft tissue destructive pathologies. Whilst anti-cytokine therapies have been successfully applied in the treatment of these diseases, this approach is yet to be attempted in cases of pulp inflammation. This review therefore focuses on the similarities in the aetiology between chronic inflammatory diseases and pulpitis, and explores how anti-cytokine therapies could be applied to manage an inflamed pulp and facilitate healing. Further proof-of-concept studies and clinical trials are justified to determine the effectiveness of these treatments to enable more predictable outcomes in VPT.

Investigation of PPARβ/δ within Human Dental Pulp Cells: A Preliminary In Vitro Study

Controlling the inflammatory response to restore tissue homeostasis is a crucial step to maintain tooth vitality after pathogen removal from caries-affected dental tissues. The nuclear peroxisome proliferator-activated receptor beta/delta (PPARβ/δ) is a ligand-activated transcription factor with emerging anti-inflammatory roles in many cells and tissues. However, its expression and functions are poorly understood in human dental pulp cells (hDPCs). Thus, this study evaluated PPARβ/δ expression and assessed the anti-inflammatory effects evoked by activation of PPARβ/δ in lipopolysaccharide- (LPS-) induced hDPCs. Our results showed that hDPCs constitutively expressed PPARβ/δ mRNA/protein, and treatment with LPS increased PPARβ/δ mRNA expression. The selective PPARβ/δ agonist GW0742 significantly decreased inflammation-related mRNA expression in hDPCs (IL6, IL1β, TNFα, MMP1, and MMP2) and RAW264.7 cells (Il6 and Tnfα). Further, PPARβ/δ agonist attenuated MMP2/9 gelatinolytic activity in hDPCs. Previously LPS-conditioned hDPCs increased the migration of RAW264.7 cells through the membrane of a Transwell coculture system. Conversely, pretreatment with GW0742 markedly decreased macrophage recruitment. These findings provide among the first evidence that hDPCs express PPARβ/δ. In addition, they suggest that activation of PPARβ/δ by GW0742 can attenuate some cellular and molecular in vitro aspects related to the inflammatory process, pointing out to investigate its potential target role in dental pulp inflammation.

Clinical cell-based versus cell-free regenerative endodontics: clarification of concept and term

There is no consensus on the true meaning of clinical regenerative endodontics, and there is confusion over the concept and the term. Commonly used terms include revitalization and revascularization. The clinical methods for endodontic revitalization procedures and the tissue engineering concept differ depending on whether there is exogenous delivery of cells - called cell therapy, or not. Here, in this review, the difference is clarified by emphasizing the correct terminology: cell-free versus cell-based regenerative endodontic therapy (CF-RET versus CB-RET). The revitalization procedures practised clinically do not fit into the modern tissue engineering concepts of pulp regeneration but can be categorized as CF-RET. The modern tissue engineering concept in pulp regeneration is a CB-RET, which so far is at the clinical trial stage. However, histological examination of teeth following regenerative endodontic treatments reveals healing with repair derived from stem cells that originate from the periodontal, bone and other tissues. The aim of regenerative endodontics is regeneration of the pulp-dentine complex. This review discusses why CF-RET is unlikely to regenerate a pulp-dentine complex with current protocols. The American Association of Endodontists and the European Society of Endodontology have not yet recommended autologous stem cell transplantation (CB-RERT) which aspires for regeneration. Therefore, an understanding of the concept, term, difficulties and differences in current protocols is important for the clinician. However, rather than being discouraged that ideal regeneration has not been achieved to date, repair can be an acceptable outcome in clinical regenerative endodontics as it has also been accepted in medicine. Repair should also be considered in the context that resolution of the clinical signs/symptoms of pulp necrosis/apical periodontitis is generally reliably obtained in clinical regenerative endodontics.

A novel bio-active adhesive monomer induces odontoblast differentiation: a comparative study

AIM

To evaluate the in vitro effect of the novel adhesive monomer CMET, a calcium salt of 4-methacryloxyethyl trimellitate (4-MET), on the proliferation, mineralization and differentiation of odontoblast-like cells, comparing with 4-MET, calcium hydroxide (CH) and mineral trioxide aggregate (MTA).

METHODOLOGY

Rat odontoblast-like MDPC-23 cells were cultured in Dulbecco's modified Eagle's medium (DMEM) supplemented with 5% foetal bovine serum. The powder of four tested materials (CMET, 4-MET, CH and MTA) was first dissolved in distilled water (dH₂O) and then was diluted by DMEM to yield final concentrations. Solvent (dH₂O) was used as a control. Cell viability was assessed using CCK-8 assay. Real-time RT-PCR was used to quantify the mRNA expression of odontogenic markers, cytokines and integrins. Mineralization inducing capacity was evaluated by alkaline phosphatase (ALPase) activity and alizarin red S staining. Statistical analyses were performed using one-way anova and post hoc Tukey's HSD test, with the significance level at 1%.

RESULTS

Cell viability was significantly greater in the CMET- (83 to 828 mmol L^-1), CH- and MTA-treated (low concentrations) groups than that in the control group (P < 0.01). Higher concentrations of each material decreased the viable cells to different extents (P < 0.01). CMET treatment augmented the expression of several integrin subunits and exhibited the highest mRNA expression levels of odontogenic markers among all groups (P < 0.01). CH and MTA treatment caused significantly greater upregulation of pro-inflammatory cytokines expression than the other groups (P < 0.01). The calcific deposition of MDPC-23 cells was dose-dependently accelerated by the addition of CMET (P < 0.01); the enhancement of mineralization was also found in the fresh prepared CH and MTA treatments. Besides, CMET showed consistency in mineralization induction after 8 weeks storage. Exposure to SB202190, a specific p38 mitogen-activated protein kinases inhibitor, significantly decreased the ALPase activity as well as the mineral deposition which was enhanced by CMET treatment (P < 0.01).

CONCLUSIONS

The novel bio-active monomer had the lowest cytotoxicity among all groups and it induced the proliferation, mineralization and differentiation of odontoblast-like cells under appropriate concentrations. This adhesive monomer possesses excellent biocompatibility and hence exhibits great potential in dentine regeneration.

Lipoteichoic acid stimulates the proliferation, migration and cytokine production of adult dental pulp stem cells without affecting osteogenic differentiation

AIM

To model in vitro the contact between adult dental pulp stem cells (DPSCs) and lipoteichoic acid (LTA), a cell wall component expressed at the surface of most Gram-positive bacteria.

METHODOLOGY

Human DPSCs obtained from impacted third molars were cultured and exposed to various concentrations of S. aureus LTA (0.1, 1.0 and 10 µg mL^-1 ). The effects of LTA on DPSCs proliferation and apoptosis were investigated by MTT assay and flow cytometry. Mineralization of DPSCs was evaluated by alizarin red staining assay. Migration was investigated by microphotographs of wound-healing and Transwell migration assays. Reverse transcription polymerase chain reaction was used to examine the effects of LTA on p65 NF-κB translocation and TLR1, TLR2 or TLR6 regulation. Enzyme-linked immunosorbent assay was used to investigate LTA-stimulated DPSCs cytokine production. One-way or two-way ANOVA and Tukey post hoc multiple comparison were used for statistical analysis.

RESULTS

DPSCs expressed TLR1, TLR2 and TLR6 involved in the recognition of various forms of LTA or lipoproteins. Exposure to LTA did not up- or down-regulate the mRNAs of TLR1, TLR2 or TLR6 whilst LPS acted as a potent inducer of them [TLR1 (P ≤ 0.05), TLR2 (P ≤ 0.001) and TLR6 (P ≤ 0.001)]. Translocation of p65 NF-κB to the nucleus was detected in LTA-stimulated cells, but to a lesser extent than LPS-stimulated DPSCs (P ≤ 0.001). The viability of cells exposed to LTA was greater than unstimulated cells, which was attributed to an increased proliferation and not to less cell death [LTA 1 μg mL^-1 (P ≤ 0.001) and 10 μg mL^-1 (P ≤ 0.01)]. For specific doses of LTA (1.0 µg mL^-1 ), adhesion of DPSCs to collagen matrix was disturbed (P ≤ 0.05) and cells enhanced their horizontal mobility (P ≤ 0.001). LTA-stimulated DPSCs released IL-6 and IL-8 in a dose-dependent manner (P ≤ 0.0001). At all concentrations investigated, LTA did not influence osteogenic/odontoblastic differentiation.

CONCLUSIONS

Human DPSCs were able to sense the wall components of Gram-positive bacteria likely through TLR2 signalling. Consequently, cells modestly proliferated, increased their migratory behaviour and contributed significantly to the local inflammatory response through cytokine release.

Evaluation of odonto/osteogenic differentiation potential from different regions derived dental tissue stem cells and effect of 17β-estradiol on efficiency

Background

The dentin is a tissue, which is formed by odontoblasts at the pulp interface of the teeth that supports the enamel. Odontoblasts, the cranial neural crest cells are derived from ectodermal mesenchymal stem cells (MSCs) and are long and polarized cells. They are present at the outer surface of dentin and play a prominent role about dentin formation. Recently, attention has been focused on induction of odontoblast using various type of MSCs and effects of the 17ß-estradiol supplementation. In this study, we establish an efficient odonto/osteoblast differentiation protocol using 17ß-estradiol supplementation while comparing the odonto/osteoblast ability of various dental MSCs.

Methods

Same donor derived four types of dental MSCs namely dental pulp stem cells (DPSCs), stem cells from apical papilla (SCAP), dental follicle stem cells (DFSCs), and periodontal ligament stem cells (PDLSCs) were evaluated for their stemness characteristics and potency towards odonto/osteoblast (Induced odonto/osteoblast) differentiation. Then 17ß-estradiol supplementation of 0 and 10 µM was applied to the odonto/osteoblast differentiation media for 14 days respectively. Furthermore, mRNA and protein levels of odonto/osteoblast markers were evaluated.

Results

All of the experimental groups displayed stemness characteristics by showing adipocyte and chondrocyte differentiation abilities, expression for cell surface markers and cell proliferation capacity without any significant differences. Moreover, all dental derived MSCs were shown to have odonto/osteoblast differentiation ability when cultured under specific conditions and also showed positive expression for odontoblast markers at both mRNA and protein level. Among all, DPSCs revealed the higher differentiation potential than other dental MSCs. Furthermore, odonto/osteoblast differentiation potential was enhanced by supplementing the differentiation media with 17ß-estradiol (E2).

Conclusions

Thus, DPSCs possess higher odonto/osteogenic potential than the SCAPs, DFSCs, PDLSCs and their differentiation capacity can by further enhanced under E2 supplementation.

Hydrogels and Dentin-Pulp Complex Regeneration: From the Benchtop to Clinical Translation

Dentin-pulp complex is a term which refers to the dental pulp (DP) surrounded by dentin along its peripheries. Dentin and dental pulp are highly specialized tissues, which can be affected by various insults, primarily by dental caries. Regeneration of the dentin-pulp complex is of paramount importance to regain tooth vitality. The regenerative endodontic procedure (REP) is a relatively current approach, which aims to regenerate the dentin-pulp complex through stimulating the differentiation of resident or transplanted stem/progenitor cells. Hydrogel-based scaffolds are a unique category of three dimensional polymeric networks with high water content. They are hydrophilic, biocompatible, with tunable degradation patterns and mechanical properties, in addition to the ability to be loaded with various bioactive molecules. Furthermore, hydrogels have a considerable degree of flexibility and elasticity, mimicking the cell extracellular matrix (ECM), particularly that of the DP. The current review presents how for dentin-pulp complex regeneration, the application of injectable hydrogels combined with stem/progenitor cells could represent a promising approach. According to the source of the polymeric chain forming the hydrogel, they can be classified into natural, synthetic or hybrid hydrogels, combining natural and synthetic ones. Natural polymers are bioactive, highly biocompatible, and biodegradable by naturally occurring enzymes or via hydrolysis. On the other hand, synthetic polymers offer tunable mechanical properties, thermostability and durability as compared to natural hydrogels. Hybrid hydrogels combine the benefits of synthetic and natural polymers. Hydrogels can be biofunctionalized with cell-binding sequences as arginine-glycine-aspartic acid (RGD), can be used for local delivery of bioactive molecules and cellularized with stem cells for dentin-pulp regeneration. Formulating a hydrogel scaffold material fulfilling the required criteria in regenerative endodontics is still an area of active research, which shows promising potential for replacing conventional endodontic treatments in the near future.

Endodontic regeneration: hard shell, soft core

A loss of organs or the destruction of tissue leaves wounds to which organisms and living things react differently. Their response depends on the extent of damage, the functional impairment and the biological potential of the organism. Some can completely regenerate lost body parts or tissues, whereas others react by forming scars in the sense of a tissue repair. Overall, the regenerative capacities of the human body are limited and only a few tissues are fully restored when injured. Dental tissues may suffer severe damage due to various influences such as caries or trauma; however, dental care aims at preserving unharmed structures and, thus, the functionality of the teeth. The dentin-pulp complex, a vital compound tissue that is enclosed by enamel, holds many important functions and is particularly worth protecting. It reacts physiologically to deleterious impacts with an interplay of regenerative and reparative processes to ensure its functionality and facilitate healing. While there were initially no biological treatment options available for the irreversible destruction of dentin or pulp, many promising approaches for endodontic regeneration based on the principles of tissue engineering have been developed in recent years. This review describes the regenerative and reparative processes of the dentin-pulp complex as well as the morphological criteria of possible healing results. Furthermore, it summarizes the current knowledge on tissue engineering of dentin and pulp, and potential future developments in this thriving field.

MicroRNA-enriched small extracellular vesicles possess odonto-immunomodulatory properties for modulating the immune response of macrophages and promoting odontogenesis

Background

To investigate the odonto-immunomodulatory properties of dental pulp stem cell-derived small extracellular vesicles (DPSCs-sEV), which promote odontogenesis by switching macrophages toward the pro-healing M2 phenotype.

Methods

MicroRNA sequencing was carried out for microRNA profiling of DPSCs-sEV. Automated Western blot, qPCR, ELISA, and flow cytometry were performed to identify the functions of microRNA-enriched DPSCs-sEV in macrophages. A luciferase reporter gene assay was carried out to confirm exosomal miR-125a-3p’s direct target gene. DPSCs-sEV-stimulated macrophage-conditioned media were used to promote odontogenesis in DPSCs and explore the mechanism of immune response in DPSCs-SEV-stimulated odontogenesis. DPSCs-sEV were injected into the exposed pulp tissue of rat incisor to investigate the odonto-immunomodulatory properties of DPSCs-sEV in vivo.

Results

DPSCs-sEV switched macrophages to the pro-healing M2 phenotype by inhibiting TLR and NFκΒ signaling. MicroRNA sequencing found 81 microRNAs significantly altered in DPSCS-sEV, with miR-125a-3p showing a 12-fold upregulation. Exosomal miR-125a-3p switched macrophages toward the M2 phenotype via inhibiting NFκΒ and TLR signaling via direct IKBKB targeting. Interestingly, DPSCs-sEV and the encapsulated miR-125a-3p enhanced BMP2 release in macrophages, promoting odontogenesis in DPSCs through BMP2 pathway activation. The rat study confirmed that DPSCs-sEV could be used as ideal biomimetic tools to enhance odontogenesis by switching macrophages toward pro-healing M2 cells.

Conclusions

We firstly defined the odonto-immunomodulatory properties of microRNA-enriched DPSCs-sEV, which could be used as ideal biomimetic tools to enhance odontogenesis by switching macrophages toward the pro-healing M2 phenotype.

Macrophage modulation of dental pulp stem cell activity during tertiary dentinogenesis

The interaction between immune cells and stem cells is important during tissue repair. Macrophages have been described as being crucial for limb regeneration and in certain circumstances have been shown to affect stem cell differentiation in vivo. Dentine is susceptible to damage as a result of caries, pulp infection and inflammation all of which are major problems in tooth restoration. Characterising the interplay between immune cells and stem cells is crucial to understand how to improve natural repair mechanisms. In this study, we used an in vivo damage model, associated with a macrophage and neutrophil depletion model to investigate the role of immune cells in reparative dentine formation. In addition, we investigated the effect of elevating the Wnt/β-catenin pathway to understand how this might regulate macrophages and impact upon Wnt receiving pulp stem cells during repair. Our results show that macrophages are required for dental pulp stem cell activation and appropriate reparative dentine formation. In addition, pharmacological stimulation of the Wnt/β-catenin pathway via GSK-3β inhibitor small molecules polarises macrophages to an anti-inflammatory state faster than inert calcium silicate-based materials thereby accelerating stem cell activation and repair. Wnt/β-catenin signalling thus has a dual role in promoting reparative dentine formation by activating pulp stem cells and promoting an anti-inflammatory macrophage response.

A macroscopic and histological analysis of radiographically well-defined deep and extremely deep carious lesions: carious lesion characteristics as indicators of the level of bacterial penetration and pulp response

AIM

To investigate the relationship between radiographically and macroscopically well-defined carious lesions and the dentine-pulp complex with regard to: (i) level of bacterial penetration; (ii) inflammatory status including the presence of hyperplastic pulp stroma; and (iii) formation of hard and/or ectopic connective tissue.

METHODOLOGY

The material comprised 68 untreated cavitated permanent teeth divided into well-defined radiographic categories based on the lesion penetration depth: (i) deep lesions ( ≥3/4 of the dentine thickness with a radio-dense zone separating the lesion from the pulp) and (ii) extremely deep lesions (the carious lesion penetrated the entire thickness of the dentine, without a radio-dense zone). After extraction, the teeth were processed for histology. The material was scored with regard to coronal breakdown, macroscopic variables describing caries activity and histological variables describing the dentine-pulp complex (bacteria, inflammatory infiltrate, partial pulp necrosis, hyperplastic changes and hard tissue/ectopic presence of connective tissue). Interrater agreement was assessed using Cohen's kappa. Associations between variables were assessed using Pearson's chi-squared or Fisher's exact test. The effect size was reported by odds ratio (OR) and associated 95% confidence interval (CI). Level of significance was set to 5%.

RESULTS

There were significant associations between a closed environment (1-2 surfaces involved) and the presence of biofilm, retrograde demineralization and light-coloured demineralized dentine. Whereas radiographically defined deep lesions tended to have bacteria only in the primary dentine (P < 0.001, OR = 20.55, 95% CI [4.44, 107.89]), extremely deep carious lesions tended to have bacteria in contact with the pulpal tissue (P = 0.007, OR = 6.84, 95% CI [2.00, 62.83]), presence of an inflammatory infiltrate (Fisher's exact; P < 0.001) and partial pulp necrosis. Hyperplastic pulps were seen only in extremely deep lesions.

CONCLUSIONS

Unlike deep lesions, extremely deep carious lesions were often associated with severe pulp inflammation and infection. A radiographic threshold between deep and extremely deep lesions is suggested as indicator of the bacterial penetration level and the severity of the pulpal response prior to intervention.

Upregulated microRNA-126 induces apoptosis of dental pulp stem cell via mediating PTEN-regulated Akt activation

INTRODUCTION

Human dental pulp stem cells (DPSCs) have potential applications in regenerative medicine. The molecular mechanisms underlying DPSCs viability and apoptosis are not completely understood. Here, we investigated the role of miR-126 in DPSCs viability and apoptosis.

MATERIAL AND METHODS

Senescent DPSCs were compared with early passage DPSCs. real-time PCR and microARRAY were performed to identify the differential expression of miR-126, and western blot was performed to detect the expression of PTEN. MTT assay was utilized to reveal the proliferative rate of both senescent and early passage DPSCs. Flow cytometry was used to examine the apoptotic rate of DPSCs. Dual-luciferase reporter assay was carried out to detect the interaction of miR-126 and PTEN.

RESULTS

Senescent DPSCs showed a high level of apoptosis. Further study showed that miR-126 is upregulated in senescent DPSCs and its overexpression in early passaged DPSCs induced apoptosis. Phosphatase and tensin homolog gene (PTEN) was identified as a target of miR-126. PTEN was downregulated in senescent DPSCs, whereas miR-126 inhibition upregulated PTEN level, and subsequently activated Akt pathway and suppressed the apoptotic phenotype of senescent DPSCs. In addition, PTEN overexpression rescued apoptosis of DPSCs at later stage.

CONCLUSION

Our results demonstrate that the miR-126-PTEN-Akt axis plays a key role in the regulation of DPSCs apoptosis and provide a candidate target to improve the functional and therapeutic potential of DPSCs.

Dentin-Pulp Tissue Regeneration Approaches in Dentistry: An Overview and Current Trends

Conventional treatment approaches in irreversible pulpitis and apical periodontitis include the disinfection of the pulp space followed by filling with various materials, which is commonly known as the root canal treatment. Disadvantages including the loss of tooth vitality and defense mechanism against carious lesions, susceptibility to fractures, discoloration and microleakage led to the development of regenerative therapies for the dentin pulp-complex. The goal of dentin-pulp tissue regeneration is to reestablish the physiological pulp function such as pulp sensibility, pulp repair capability by mineralization and pulp immunity. Recent dentin-pulp tissue regeneration approaches can be divided into cell homing and cell transplantation. Cell based approaches include a suitable scaffold for the delivery of potent stem cells with or without bioactive molecules into the root canal system while cell homing is based on the recruitment of host endogenous stem cells from the resident tissue including periapical region or dental pulp. This review discusses the recent treatment modalities in dentin-pulp tissue regeneration through tissue engineering and current challenges and trends in this field of research.

Potential Roles of Bone Morphogenetic Protein 9 in the Odontogenic Differentiation of Dental Pulp Cells

INTRODUCTION

The differentiation of dental pulp cells (DPCs) plays an important role in the repair of dental pulp injury. Bone morphogenetic protein 9 (BMP9) is one of the most effective BMPs to induce the differentiation of stem cells. However, the role of BMP9 in promoting the odontogenic differentiation of DPCs and dentinogenesis is worth knowing.

METHODS

Fluorescence in situ hybridization and immunohistochemistry staining were performed to detect the BMP9 expression in human dental pulp. BMP9 was overexpressed in human DPCs (hDPCs), and the mineralization of hDPCs was tested by alkaline phosphatase staining and alizarin red staining. The expression of odontogenic differentiation-related genes was examined by quantitative real-time polymerase chain reaction and western blotting. The subcutaneous transplantation experiment was performed to test the odonto-induction ability of BMP9 in vivo. The rat direct pulp-capping experiment was performed to test the function of BMP9 in promoting dentin formation.

RESULTS

BMP9 showed an increased expression in odontoblast layer at both the mRNA and protein levels. BMP9 enhanced the mineralization and induced the expression of odontogenic differentiation-related genes in hDPCs. More mineralized nodules, and increased expression of dentin sialophosphoprotein (DSPP) and dentin matrix protein-1 (DMP1) were detected in the beta-tricalcium phosphate scaffold/cells composites of BMP9 group compared with the control group. Meanwhile, there was thicker reparative dentin formation in the BMP9 group in the rat pulp exposure experiment.

CONCLUSIONS

BMP9 participates in the process of DPC differentiation and promotes DPC mineralization and dentinogenesis. BMP9 might be a potential therapeutic target in the repair of dental pulp injury.

MicroRNA-223 negatively regulates LPS-induced inflammatory responses by targeting NLRP3 in human dental pulp fibroblasts

AIM

To investigate the effect of miR-223 on NLRP3, subsequently regulating the production of the NLRP3/CASP1 inflammasome pathway-mediated proinflammatory cytokines IL-1β and IL-18 in human dental pulp fibroblasts (HDPFs).

METHODOLOGY

Human dental pulp tissue (HDPT) and HDPFs were obtained from impacted third molars. The miR-223 mimics and inhibitor or NLRP3 plasmid were used to upregulate or downregulate miR-223 or NLRP3 in HDPFs, respectively. Computational prediction via TargetScan 5.1 and a luciferase reporter assay was conducted to confirm target association. The mRNA and protein expression of NLRP3, caspase-1, IL-1β and IL-18 was determined by qRT-PCR and Western blotting, respectively. The release of IL-1β and IL-18 was analysed by ELISA. The significance of the differences between the experimental and the control groups was determined using one-way analysis of variance; P < 0.05 indicated statistical significance.

RESULTS

A decrease in miR-223 and an increase in NLRP3 in HDPT occurred during the transformation of reversible pulpitis into irreversible pulpitis compared to that in healthy pulp tissue (P < 0.05). The computational prediction and luciferase reporter assay confirmed that NLRP3 was a direct target of miR-223 in HDPFs. The miR-223 inhibitor further promoted ATP plus LPS-induced NLRP3/CASP1 inflammasome pathway activation compared to the ATP plus LPS-induced group (P < 0.05). In contrast, the miR-223 mimic significantly inhibited the NLRP3/CASP1 inflammasome pathway activation induced by ATP plus LPS compared to the ATP plus LPS-induced group (P < 0.05).

CONCLUSION

MiR-223 served as a negative regulator involved in the control of the production and secretion of proinflammatory cytokines mediated by the NLRP3/CASP1 inflammasome pathway by targeting NLRP3. These data provide insight into the potential regulatory effects of miRNAs on the NLRP3 inflammasome, thus opening up novel potential therapeutic avenues for future endodontic treatment.

Diagnostic biomarker candidates for pulpitis revealed by bioinformatics analysis of merged microarray gene expression datasets

Background

Pulpitis is an inflammatory disease, the grade of which is classified according to the level of inflammation. Traditional methods of evaluating the status of dental pulp tissue in clinical practice have limitations. The rapid and accurate diagnosis of pulpitis is essential for determining the appropriate treatment. By integrating different datasets from the Gene Expression Omnibus (GEO) database, we analysed a merged expression matrix of pulpitis, aiming to identify biological pathways and diagnostic biomarkers of pulpitis.

Methods

By integrating two datasets (GSE77459 and GSE92681) in the GEO database using the sva and limma packages of R, differentially expressed genes (DEGs) of pulpitis were identified. Then, the DEGs were analysed to identify biological pathways of dental pulp inflammation with Gene Ontology (GO) analysis, Kyoto Encyclopedia of Genes and Genomes (KEGG) pathway enrichment analysis and Gene Set Enrichment Analysis (GSEA). Protein–protein interaction (PPI) networks and modules were constructed to identify hub genes with the Search Tool for the Retrieval of Interacting Genes/Proteins (STRING) and Cytoscape.

Results

A total of 470 DEGs comprising 394 upregulated and 76 downregulated genes were found in pulpitis tissue. GO analysis revealed that the DEGs were enriched in biological processes related to inflammation, and the enriched pathways in the KEGG pathway analysis were cytokine-cytokine receptor interaction, chemokine signalling pathway and NF-κB signalling pathway. The GSEA results provided further functional annotations, including complement system, IL6/JAK/STAT3 signalling pathway and inflammatory response pathways. According to the degrees of nodes in the PPI network, 10 hub genes were identified, and 8 diagnostic biomarker candidates were screened: PTPRC, CD86, CCL2, IL6, TLR8, MMP9, CXCL8 and ICAM1.

Conclusions

With bioinformatics analysis of merged datasets, biomarker candidates of pulpitis were screened and the findings may be as reference to develop a new method of pulpitis diagnosis.

Three-dimensional qualitative and quantitative analyses of the effect of periradicular lesions on the outcome of regenerative endodontic procedures: A prospective clinical study

OBJECTIVES

Qualitative and quantitative evaluation of the outcomes of regenerative endodontic procedure (REP) on human immature necrotic teeth with apical periodontitis using cone-beam computed tomography (CBCT) MATERIALS AND METHODS: Immature permanent teeth (n = 50) with necrotic pulp and periradicular pathosis were treated with a cell-homing concept-based REP. Following the procedure, a limited field-of-view CBCT scan was obtained. At each recall session (6, 12, 18 months), clinical tests were performed, and a digital periapical radiograph was taken. When significant radiographic changes were evident in the follow-up, a final CBCT scan was taken for qualitative and quantitative assessment. These initial and follow-up CBCT scans were assessed for quantification of changes in root length, pulp space diameter and periradicular lesion size. The data were statistically analysed using t test, one-way ANOVA, post hoc test and paired t test (P = 0.05).

RESULTS

Of the teeth, 94.6% were clinically successful based on the lack or regression of signs and symptoms after 48 months follow-up. REP resulted in a statistically significant increase in root length, decrease in pulp space diameter and periradicular radiolucency (P < 0.05). CBCT images illustrated various patterns of root maturation including an increased thickening of the canal walls and continued root maturation (37.1%), continued root development with the apical foramen remaining open (57.1%), severe calcification (obliteration) of the canal space (2.9%) and hard tissue barrier formation in the canal space between the coronal plug and the root apex (2.9%).

CONCLUSION

This study highlighted that the expected outcome of radiographic root development was less predictable when immature permanent teeth with periradicular pathosis were treated with REP.

CLINICAL RELEVANCE

The size and extent (expansion/destruction of the cortical plate) of periradicular lesions and abscesses influence the outcome of REP. These factors must be taken into consideration during treatment planning.

Efficacy of different calcium silicate materials as pulp-capping agents: Randomized clinical trial

Background/purpose

Calcium hydroxide-based materials were the gold standard in vital pulp therapies for decades' despite of several shortcomings. However, calcium silicates have been discussed as an alternative to overcome these drawbacks. It was aimed to investigate the in-vivo effectiveness of different calcium silicates based materials in pulp capping in this study.

Materials and methods

A parallel-design, randomized controlled trial with 213 patients who has deep dentin caries, vital pulps and without spontaneous pain or history of swelling was designed. 525 M teeth were randomized, blinded and allocated to one of the five groups for pulp capping treatment (n = 105). All teeth were followed up clinically and radiographically (after 1st, 6th, 12th and 36th months) by blinded investigators. The clinical and radiographic success, and the effect of the pulp exposure to the success rate analyzed with Wald chi-square and Z tests.

Results

Clinical and radiographic success of MTA+ (86.3%, 85.4%) and Biodentine (79.4%, 80.1%) were found the highest. Although results of Theracal LC group (72.1%, 73.6%) were better than Dycal group (69.4%, 70.2%), the difference was nonsignificant (p > 0.05). Only in light-cured groups, (TheraCal LC & LC Calcihyd) pulpal exposure size effected the success of the materials (p < 0.05). MTA+ and Biodentine resulted better scores, when compared with TheraCal LC in large pulpal exposures (p < 0.05).

Conclusion

After 36-month follow-up, both MTA+ and Biodentine were found to be the appropriate material for direct pulp capping in permanent teeth. The filler ingredient of the Theracal-LC eases the usage of calcium silicates but decreases the success rate.

Equivalence of human and bovine dentin matrix molecules for dental pulp regeneration: proteomic analysis and biological function

OBJECTIVE

To compare proteomics and biological function of human dentin matrix molecules (hDMMs) and bovine dentin matrix molecules (bDMMs).

DESIGN

Dentin powder from human or bovine teeth (n = 4) was demineralized in 10% (v/v) ethylenediaminetetraacetic acid for 7 days. The extracts were dialyzed, lyophilized and proteins were characterized using liquid chromatography-tandem mass spectrometry and shotgun proteomic analysis. To study biological function, mouse-derived undifferentiated dental pulp cells (OD21) were treated with 0.01, 0.1 or 1 μg/mL of hDMMs or bDMMs and proliferation was measured after 24 hours and 48 hours using 3-(4,5-Dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) assay. Cell migration was assessed after 24 hours using a Boyden chamber. Alizarin Red S staining was used to evaluate mineral formation.

RESULTS

There were 307 proteins identified, of which 93 proteins were common to both species. Gene Ontology functional analysis demonstrated similar pattern of biological process in both species which consisted mainly of tissue development and biomineralization. hDMMs and bDMMs both enhanced cell proliferation. After 24 hours, all concentrations of bDMMs promoted cell proliferation (p ≤ 0.05), while hDMMs did not affect proliferation. After 48 hours, groups with 1μg/mL of bDMMs and 0.01μg/mL of hDMMs had increased cell proliferation compared to control (p ≤ 0.0001). All concentrations of hDMMs and bDMMs enhanced cell migration and mineralization (p ≤ 0.0001).

CONCLUSION

bDMMs has similar biological functions as hDMMs. Moreover, bDMMs stimulated cell proliferation, migration and differentiation similar to hDMMs.

Potential Application of Human β-Defensin 4 in Dental Pulp Repair

When pulp tissue is damaged by caries or trauma, vital pulp therapy (VPT) can help preserve the pulp tissue for long-term retention of teeth. However, the choice of pulp capping agent used in VPT is important for the successful preservation of the pulp tissue. Here we investigated the expression and biological function of human β-defensin 4 (HBD4) in dental pulp stem cells (DPSC) and explored its potential as a pulp capping agent. We examined the expression of HBD4 in DPSC in vitro using qPCR and immunofluorescence staining. We also looked at the effect of HBD4 on inflammatory factors in lipopolysaccharide (LPS)-stimulated DPSC, and its effects on mineralizing cell phenotype differentiation, via qPCR and western blot. Finally, we examined the ability of HBD4 to promote the restoration of the pulp-dentin complex in vivo, using male Wistar rats with reversible pulpitis. We found HBD4 was highly expressed in DPSC stimulated by TNF-α and IL-1α. HBD4 down-regulated the expression of inflammatory mediators (i.e., IL-1α, IL-1β, IL-6, TNF-α) in LPS-stimulated DPSC, and suppressed MAPK activity and the NF-κB pathway. HBD4 also enhanced the differentiation of DPSC into osteoblasts or odontoblasts, potentially by modulating the Notch pathway. Furthermore, HBD4 controlled the degree of pulp inflammation in a rat model of reversible pulpitis and induced the formation of restorative dentin. Together our findings indicate HBD4 may be a useful pulp capping agent for use in VPT.

Controlled release of odontogenic exosomes from a biodegradable vehicle mediates dentinogenesis as a novel biomimetic pulp capping therapy

Mineralized enamel and dentin provide protection to the dental pulp, which is vital tissue rich with cells, vasculature, and nerves in the inner tooth. Dental caries left untreated threaten exposure of the dental pulp, providing facile access for bacteria to cause severe infection both in the pulp and systemically. Dental materials which stimulate the formation of a protective dentin bridge after insult are necessary to seal the pulp chamber in an effort to maintain natural dentition and prevent pulpal infection. Dental materials to date including calcium hydroxide paste, mineral trioxide aggregate, and glass ionomer resin, are used with mixed results. Herein we exploited the cell-cell communicative properties of exosomes, extracellular vesicles derived from both mineralizing primary human dental pulp stem cells (hDPSCs) and an immortalized murine odontoblast cell line (MDPC-23), to catalyze the formation of a reactionary dentin bridge by recruiting endogenous stem cells of the dental pulp, through an easy-to-handle delivery vehicle which allows for their therapeutic controlled delivery at the pulp interface. Exosomes derived from both hDPSCs and MDPCs upregulated odontogenic gene expression and increased mineralization in vitro. We designed an amphiphilic synthetic polymeric vehicle from a triblock copolymer which encapsulates exosomes by polymeric self-assembly and maintains their biologic integrity throughout release up to 8-12 weeks. The controlled release of odontogenic exosomes resulted in a reparative dentin bridge formation, superior to glass-ionomer cement alone in vivo, in a rat molar pulpotomy model after six weeks. We have developed a platform for the encapsulation and controlled, tunable release of cell-derived exosomes, which maintains their advantageous physiologic properties reflective of the donor cells. This platform is used to modulate downstream recipient cells towards a designed dentinogenic trajectory in vitro and in vivo. Additionally, we have demonstrated the utility of an immortalized cell line to produce a high yield of exosomes with cross-species efficacy.