Pulp-Dentin Tissue Healing Response: A Discussion of Current Biomedical Approaches

Non-Surgical Endodontic Management of Large Periapical Lesions After Traumatic Dental Injuries

Traumatic dental injuries of permanent teeth result in multiple immediate and long-term consequences depending upon the severity of trauma, age of the patient, the status of root maturity, and the emergency care provided. The healing responses may get disturbed due to severe damage, loss of vascularity of the supporting structures, and infections. As a result, the prohealing mediators and pathways are overpowered by the destructive stimuli often manifested by an increased osteoclastic activity. Among the various late complications, the apical periodontitis or the periapical lesions are most worrisome for the patients and create clinical dilemma for the dentists. In the past, many such lesions were classified as cysts and subjected to surgical management. However, better understanding of lesion pathophysiology, three-dimensional imaging, and molecular pathways have established their inflammatory nature. The advancements in materials such as calcium silicates, and regenerative techniques have propelled the research related to non-surgical endodontic management as its clinical acceptability. The treatment largely follows the recommendations of regenerative medicine and is based on four principles: (a) establishing the drainage or an endodontic access to the area, (b) removal of most of the triggering agents such as necrosed pulp, toxins, and inflammatory mediators, (c) disinfection of the area, controlling inflammation and reversal of the acidic pH, and (d) maintenance of this infection/inflammation-free state for a long time through adequate sealing. This review aims to highlight the rationale of the approach, case selection, pathophysiology of the causation and healing, clinical protocols, and the limitations of non-surgical endodontic management of large periapical lesions secondary to traumatic dental injuries.

Dental pulp stem cells - A basic research and future application in regenerative medicine

Dental pulp is a valuable and accessible source of stem cells (DPSCs) with characteristics similar to mesenchymal stem cells. DPSCs can regenerate a range of tissues and their potential for clinical application in regenerative medicine is promising. DPSCs have been found to express low levels of Class II HLA-DR (MHC) molecules, making them potential candidates for allogeneic transplantation without matching the donor's tissue. Research on the correlation between non-coding RNAs (ncRNAs) and human dental pulp stem cells (DPSCs) provides promising insights into the use of these cells in clinical settings for a wide range of medical conditions. It is possible to use a number of ncRNAs in order to restore the functional role of downregulated ncRNAs that are correlated with osteoblastogenesis, or to suppress the functional role of overexpressed ncRNAs associated with osteoclast differentiation in some cases.

The role of vitamin D receptor in predentin mineralization and dental repair after injury

Dentin is a permeable and complex tubular composite formed by the mineralization of predentin that mineralization and repair are of considerable clinical interest during dentin homeostasis. The role of Vdr, a receptor of vitamin D, in dentin homeostasis remains unexplored. The aim of the present study was to assess the impact of Vdr on predentin mineralization and dental repair. Vdr-knockout (Vdr-/-) mice models were constructed; histology and immunohistochemistry analyses were conducted for both WT and Vdr-/- mice. The finding revealed a thicker predentin in Vdr-/- mice, characterized by higher expression of biglycan and decorin. A dental injury model was employed to observe tertiary dentin formation in Vdr-/- mice with dental injuries. Results showed that tertiary dentin was harder to form in Vdr-/- mice with dental injury. Over time, heightened pulp invasion was observed at the injury site in Vdr-/- mice. Expression of biglycan and decorin was reduced in the predentin at the injury site in the Vdr-/- mice by immunohistochemistry. Taken together, our results imply that Vdr plays a regulatory role in predentin mineralization and tertiary dentin formation during dentin homeostasis.

Analysis of the cytotoxicity and bioactivity of CeraSeal, BioRoot™ and AH Plus® sealers in pre-osteoblast lineage cells

BACKGROUND

The objective of the present study was to evaluate in vitro the cytotoxicity and bioactivity of various endodontic sealers (CeraSeal, BioRoot™ and AH Plus®) in pre-osteoblast mouse cells (MC3T3 cells).

METHODS

MC3T3 cells (ATCC CRL-2594) were plated in 1 × 104 cells/well in 96-well plates in contact with endodontic sealers at concentrations of 1:10 and 1:100. Cell viability was evaluated by MTT assay after 24 and 48 h. In addition, sealer bioactivity was measured by RT-PCR for mediator of inflammation (Tnf, Ptgs2) and mineralization (Runx2, Msx1, Ssp1 and Dmp1) after 24 h and by Alizarin Red S Assay of mineralization after 28 days. Data were analyzed using one-way ANOVA followed by the Tukey's post-test at a significance level of 5%.

RESULTS

BioRoot™ presented 24-hour cytotoxicity (p < 0.05) at 1:10 concentration. In the period of 48 h, no endodontic cement was cytotoxic to the cells compared to the control (p > 0.05). TNF-α gene expression was induced by AH Plus® (p < 0.05), while Ptgs2 was induced by the CeraSeal and BioRoot™ (p < 0.05). The expression of Runx2 was stimulated by BioRoot™ and AH Plus® (p < 0.05). In contrast, the expression of Dmp-1 Dmp1 was higher for the CeraSeal and BioRoot™ (p < 0.05). Nonetheless, the sealers did not impact the formation of mineralization nodules (p > 0.05).

CONCLUSION

CeraSeal, BioRoot™ and AH Plus® sealers were not cytotoxic to MC3T3 cells within 48 h, but differentially induced the expression of genes related to inflammation and mineralization without impacting biomineralization by the cells.

Wound-healing Processes After Pulpotomy in the Pulp Tissue of Type 1 Diabetes Mellitus Model Rats

INTRODUCTION

Patients with type 1 diabetes mellitus (DM1) tend to have delayed wound healing, even in the pulp tissue. We hypothesized that hyperglycemia affects odontoblast-like cell (OLC) differentiation and is involved in macrophage polarization. Accordingly, we evaluated dental pulp stem cell differentiation and macrophage phenotypes after pulpotomy.

METHODS

After modifying DM1 rat models by streptozotocin, 8-week-old rats' upper left first molars were pulpotomized with mineral trioxide aggregate. Meanwhile, the control group was administered saline. Immunohistochemical localization of nestin, osteopontin, α-smooth muscles (α-SMAs), and CD68 (pan-macrophage marker) was conducted 7 days after pulpotomy. The OLC differentiation stage was determined using double immunofluorescence of nestin and α-SMA. Double immunofluorescence of CD68 and iNOS was counted as M1 macrophages and CD68 and CD206 as M2 macrophages. Proliferating cell nuclear antigen and Thy-1 (CD90) were evaluated by immunofluorescence.

RESULTS

In DM1 rats, the reparative dentin bridge was not complete; however, the osteopontin-positive area did not differ significantly from that in controls. Proliferating cell nuclear antigen, indicative of cell proliferation, increased in positive cells in DM1 rats compared with controls. Double-positive cells for α-SMA and nestin indicated many immature OLCs in DM1. CD90 was positive only in controls. CD68-positive cells, especially M1 macrophages, were increased in DM1 rats, allowing the inflammatory stage to continue 7 days after pulpotomy.

CONCLUSIONS

The condition of DM1 model rats can interfere at various stages of the wound healing process, altering OLC differentiation and macrophage polarization. These findings highlight the importance of normal blood glucose concentrations during pulp wound healing.

Viability of human dental pulp stem cells: The potential of L-arginine-based culture media

Dental pulp is built by proteins that have various roles in the biological process of pulp, such as structural protein, regulation protein, and catalytic protein. L-arginine, an amino acid and one of the building blocks of proteins, regulates pro-inflammatory and anti-inflammatory activity. Therefore, L-arginine-based culture has potential to promote dental pulp regeneration. This study aimed to investigate the potential of L-arginine-based culture in improving the viability of human dental pulp stem cells (hDPSCs). We evaluated the viability of hDPSCs in culture media supplemented with different concentrations of L-arginine amino acid (250, 300, 350, and 400 µmol/L) and Dulbecco's Modified Eagle Medium plus fetal bovine serum 10% (control) using a 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide assay after 24-h incubation time. Statistical analysis was conducted using a one-way analysis of variance and post hoc least significant difference test. In qualitative analysis, the 4´, 6-diamidino-2-phenylindole staining method was used. The evaluation has shown a significant result when 250, 300, and 350 μmol/L concentration of L-arginine amino acid culture media compared with control, and 400 μmol/L has the best result and was not significantly different with control toward viability of hDPSCs.

Wnt3a-Loaded Hydroxyapatite Nanowire@Mesoporous Silica Core-Shell Nanocomposite Promotes the Regeneration of Dentin-Pulp Complex via Angiogenesis, Oxidative Stress Resistance, and Odontogenic Induction of Stem Cells

Pulp exposure often leads to pulp necrosis, root fractures, and ultimate tooth loss. The repair of the exposure site with pulp capping treatment is of great significance to preserving pulp vitality, but its efficacy is impaired by the low bioactivity of capping materials and cell injuries from the local accumulation of oxidative stress. This study develops a Wnt3a-loaded hydroxyapatite nanowire@mesoporous silica (Wnt3a-HANW@MpSi) core-shell nanocomposite for pulp capping treatments. The ultralong and highly flexible hydroxyapatite nanowires provide the framework for the composites, and the mesoporous silica shell endows the composite with the capacity of efficiently loading/releasing Wnt3a and Si ions. Under in vitro investigation, Wnt3a-HANW@MpSi not only promotes the oxidative stress resistance of dental pulp stem cells (DPSCs), enhances their migration and odontogenic differentiation, but also exhibits superior properties of angiogenesis in vitro. Revealed by the transcriptome analysis, the underlying mechanisms of odontogenic enhancement by Wnt3a-HANW@MpSi are closely related to multiple biological processes and signaling pathways toward pulp/dentin regeneration. Furthermore, an animal model of subcutaneous transplantation demonstrates the significant reinforcement of the formation of dentin-pulp complex-like tissues and blood vessels by Wnt3a-HANW@MpSi in vivo. These results indicate the promising potential of Wnt3a-HANW@MpSi in treatments of dental pulp exposure.

Application of neurotransmitters and dental stem cells for pulp regeneration: A review

Introduction

Although there have been many studies on stem cells, few have investigated how neurotransmitters and stem cell proliferation interact to regenerate dental pulp. Dental pulp regeneration is an innovative procedure for reviving dental pulp, if feasible for the entire tooth. Upon tooth injury, activated platelets release serotonin and dopamine in bulk to mobilize dental pulp stem cells to mediate natural dental repair. This has induced research on the role of neurotransmitters in increasing the proliferation rate of stem cells. This review also covers prospective future treatments for dental pulp regeneration.

Methods

A literature search was performed via PubMed and ScienceDirect from 2001 to 2022, using the keywords "neurotransmitter," "stem cell," "tooth regeneration," "tooth repair," "regenerative dentistry," and "dental pulp." Different inclusion/exclusion criteria were used, and the search was restricted to English articles.

Results

Nine publications reporting neurotransmitter interactions with stem cells for tooth and pulp regeneration were selected.

Conclusion

Neurotransmitters were found to interact with dental stem cells. Evidence pointing to neurotransmitters as a factor in the increased proliferation of stem cells was found. This review thus gives hope for tooth pulp regeneration and repair.

Heat generated during dental treatments affecting intrapulpal temperature: a review

INTRODUCTION

Heat is generated and transferred to the dentine-pulp complex during various dental procedures, such as from friction during cavity preparations, exothermic reactions during the polymerisation of restorative materials and when polishing restorations. For in vitro studies, detrimental effects are possible when intra-pulpal temperature increases by more than 5.5°C (that is, the intra-pulpal temperature exceeds 42.4°C). This excessive heat transfer results in inflammation and necrosis of the pulp. Despite numerous studies stating the importance of heat transfer and control during dental procedures, there are limited studies that have quantified the significance. Past studies incorporated an experimental setup where a thermocouple is placed inside the pulp of an extracted human tooth and connected to an electronic digital thermometer.

METHODS

This review identified the opportunity for future research and develop both the understanding of various influencing factors on heat generation and the different sensor systems to measure the intrapulpal temperature.

CONCLUSION

Various steps of dental restorative procedures have the potential to generate considerable amounts of heat which can permanently damage the pulp, leading to pulp necrosis, discoloration of the tooth and eventually tooth loss. Thus, measures should be undertaken to limit pulp irritation and injury during procedures. This review highlighted the gap for future research and a need for an experimental setup which can simulate pulp blood flow, temperature, intraoral temperature and intraoral humidity to accurately simulate the intraoral conditions and record temperature changes during various dental procedures.

Histopathological Biocompatibility Evaluation of TheraCal PT, NeoMTA, and MTA Angelus in a Murine Model

The aim of this study was to evaluate the biocompatibility of the regeneration of the dentin-pulp complex in a murine model with different treatments with MTA Angelus, NeoMTA, and TheraCal PT. An in vivo controlled experimental study of 15 male Wistar rats forming three study groups, the upper and lower central incisors were selected where pulpotomies were conducted, leaving a central incisor as control at 15, 30, and 45 days. For data analysis, these were expressed as mean ± standard deviation and were examined by Kruskal-Wallis test. Three factors were analyzed as follows: "inflammatory infiltrate; disorganization of pulp tissue, and the formation of reparative dentin". No statistical significance was found between the different groups (p > 0.05). Treatment with these three biomaterials (MTA, TheraCal PT, and Neo MTA) presented an inflammatory infiltrate and slight disorganization of the odontoblast layer in the pulp tissue of a murine model, with normal coronary pulp tissue and the formation of reparative dentin in the three experimental groups. Thus, we are able to conclude that all three are biocompatible materials.

CaCO3 from Anadara granosa shell as reparative dentin inducer in odontoblast pulp cells: In-vivo study

Introduction

Anadara granosa (blood clam) shell contained 98.7% of calcium carbonate (CaCO3). This material has bio-properties that able to induced the dentin regeneration. This study is expected to reveal the nuclear factor kappa beta (NF-kB), transforming growth factor beta (TGF-β1), and vascular endothelial growth factor A (VEGF-A) expression in dental pulp after application of CaCO3 from Anadara granosa shell.

Material and methods

The thirty Rattus norvegicus strain Wistar used as model. The maxillary first molar was preparation using 0.84 mm low-speed diamond bur to made cavity. The cavity then applied glass ionomer cement (as control group) and other group applied CaCO3 from Anadara granosa shell. The teeth in each group were extracted after 1st, 3rd and 7th days of application for immunohistochemistry analysis for NF-kB, TGF-β1, and VEGF-A expression.

Result

The NF-kB expression in the group with CaCO3 from Anadara granosa shell lower than control after 1st, 3rd and 7th days (p < 0.05). In other hand, the TGF-β1 and VEGF-A expression in the group with CaCO3 from Anadara granosa shell higher than control after 1st, 3rd and 7th days (p < 0.05).

Conclusion

CaCO3 from Anadara granosa shell able to stimulate the TGF-β1 and VEGF-A and suppress the NF-kB expression in the dental pulp. This material able to develop as dentin-pulp material restoration.

The paradigm of miRNA and siRNA influence in Oral-biome

Short nucleotide sequences like miRNA and siRNA have attracted a lot of interest in Oral-biome investigations. miRNA is a small class of non-coding RNA that regulates gene expression to provide effective regulation of post-transcription. On contrary, siRNA is 21-25 nucleotide dsRNA impairing gene function post-transcriptionally through inhibition of mRNA for homologous dependent gene silencing. This review highlights the application of miRNA in oral biome including oral cancer, dental implants, periodontal diseases, gingival fibroblasts, oral submucous fibrosis, radiation-induced oral mucositis, dental Pulp, and oral lichenoid disease. Moreover, we have also discussed the application of siRNA against the aforementioned disease along with the impact of miRNA and siRNA to the various pathways and molecular effectors pertaining to the dental diseases. The influence of upregulation and downregulation of molecular effector post-treatment with miRNA and siRNA and their impact on the clinical setting has been elucidated. Thus, the mentioned details on application of miRNA and siRNA will provide a novel gateway to the scholars to not only mitigate the long-lasting issue in dentistry but also develop new theragnostic approaches.

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

Objectives

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

Materials and methods

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

Results

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

Conclusion

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

Dentin Sialoprotein/Phosphophoryn (DSP/PP) as Bio-Inductive Materials for Direct Pulp Capping

Conventional direct pulp capping, such as calcium hydroxide (Ca(OH)₂) or silicate products, usually induces an inflammatory reaction to provoke pulp regeneration. Phosphophoryn (PP) and dentin sialoprotein (DSP), the two most abundant non-collagenous proteins in the dentin matrix, are responsible for dentin mineralization, pulp cell migration, and differentiation. Here we examined the PP and combined DSP/PP as bio-inductive pulp capping materials by in vitro and in vivo tests. Firstly, the effects of the PP dose on pulp cell migration and matrix protein expression were examined by an agarose bead test. Secondly, the role of recombinant DSP (recDSP) and recDSP/PP on stimulating DSP-PP transcript expression was examined by RT-PCR. DSPP mRNA was also knocked down by RNA interference (RNAi) to examine their functions on dentin matrix mineralization. Finally, we used ferret animal models to test PP and recDSP/PP acting as capping agents on in vivo pulp responses and reparative dentin formation. The result showed that intermediate-dose PP was the most effective to enhance cell migration and differentiation. RecDSP/PP strongly enhanced the DSP-PP transcript expression, while inhibition of DSPP mRNA expression by siRNAs partially or completely affected dental pulp cell mineralization. The in vivo results showed that intermediate-dose PP and recDSP/PP proteins induced less pulp inflammation and promoted reparative dentin formation. Contrarily, conventional calcium hydroxide induced severe pulp inflammation. With these findings, DSP and PP could serve as capping agents for pulp capping therapy.

6-Bromoindirubin-3′-Oxime Regulates Colony Formation, Apoptosis, and Odonto/Osteogenic Differentiation in Human Dental Pulp Stem Cells

6-bromoindirubin-3′-oxime (BIO) is a candidate small molecule that effectively modulates Wnt signalling owing to its stable property. The present study investigated the influence of BIO on the odonto/osteogenic differentiation of human dental pulp stem cells (hDPSCs). hDPSCs were treated with 200, 400, or 800 nM BIO, and the effects on hDPSC responses and osteogenic differentiation were assessed. BIO-mediated Wnt activation was confirmed by β-catenin nuclear translocation detected by immunofluorescence staining. BIO attenuated colony formation and cell migration determined by in vitro wound-healing assay. BIO increased early apoptotic cell population evaluated using flow cytometry. For osteogenic induction, BIO promoted alkaline phosphatase (ALP) activity and mineralisation in a dose-dependent manner. ALP, RUNX2, OCN, OSX, ANKH, DMP1, and DSPP mRNA expression were significantly upregulated. The OPG/RANKL expression ratio was also increased. Further, BIO attenuated adipogenic differentiation as demonstrated by decreased lipid accumulation and adipogenic-related gene expression. Bioinformatic analysis of RNA sequencing data from the BIO-treated hDPSCs revealed that BIO modulated pathways related to autophagy and actin cytoskeleton regulation. These findings demonstrated that BIO treatment promoted hDPSC osteogenic differentiation. Therefore, this small molecule is a strong candidate as a bioactive molecule to enhance dentin repair.

Phenytoin Is Promoting the Differentiation of Dental Pulp Stem Cells into the Direction of Odontogenesis/Osteogenesis by Activating BMP4/Smad Pathway

Background

The purpose of this study was the evaluation of the potential and mechanism of phenytoin to promote differentiation of human dental pulp stem cells (hDPSC) into odontoblasts/osteoblasts.

Methods

Fourth-generation human hDPSC originating from healthy pulp of third molars was cultured in control as well as phenytoin-containing media (PHT) for 14 days. qPCR was applied to detect the expression of DSPP, DMP1, and ALP genes. Western blot analysis was used to confirm the findings. One-way analysis of variance (ANOVA) was used for statistical analysis (p < 0.05). Information about phenytoin was assessed from PubChem database, while targets of phenytoin were assessed from six databases. Drug targets were extracted based on the differentially expressed genes (‖logFC‖ ≥ 1, p < 0.05) in the experimental group (50 mg/L PHT, 14 days). GO BP and KEGG pathway enrichment analysis on the obtained drug targets was performed and the target protein functional network diagram was constructed.

Results

A concentration below 200 mg/L PHT had no obvious toxicity to hDPSC. The expression of DSPP, DMP1, and ALP genes in the 50 mg/L PHT concentration group increased significantly. The WB experiment showed that the protein content of BMP4, Smad1/5/9, and p-Smad1/5 was significantly increased in 50 mg/L PHT in comparison with the NC group (the group without treatment of PHT) at 14 days.

Conclusion

Phenytoin has the ability of promoting the differentiation of hDPSC into odontoblasts and osteoblasts. BMP4/Smad pathway, inducing odontogenic/osteogenic differentiation of hDPSC, appears a main process in this context.

Regenerative Endodontics and Minimally Invasive Dentistry: Intertwining Paths Crossing Over Into Clinical Translation

Regenerative endodontic procedures have been described for over a decade as a paradigm shift in the treatment of immature necrotic permanent teeth, owing to their ability to allow root maturation with subsequent enhancement of the tooth’s fracture resistance in addition to the potential for regeneration of vital intracanal tissues. Concomitantly, minimally invasive endodontics is another rising concept with the main concern of preservation of tooth structure. Stemming from their potential to preserve the original tooth structure, both regenerative and minimally invasive endodontics could be considered as two revolutionary sciences with one common goal. Achieving this goal would entail not only employing the appropriate strategies to recreate the ideal regenerative niche but modifying existing concepts and protocols currently being implemented in regenerative endodontics to address two important challenges affecting the outcome of these procedures; conservation of tooth structure and achieving effective disinfection. Therefore, the search for new biomimetic cell-friendly disinfecting agents and strategies is crucial if such a novel integratory concept is to be foreseen in the future. This could be attainable by advocating a new merged concept of “minimally invasive regenerative endodontic procedures (MIREPs),” through modifying the clinical protocol of REPs by incorporating a minimally invasive access cavity design/preparation and biomimetic disinfection protocol, which could enhance clinical treatment outcomes and in the future; allow for personalized disinfection/regeneration protocols to further optimize the outcomes of MIREPs. In this review, we aim to introduce this new concept, its realization and challenges along with future perspectives for clinical implementation.

Regenerative Endodontics Success Factors and their Overall Effectiveness: An Umbrella Review

Introduction

Regenerative endodontics is a developing field of dentistry and aims to recover the physiological and anatomical functions of the tooth for cases of severe dental caries, pulpal pathologies and dental trauma.

Materials and Methods

This umbrella review seeks to discover the scientific evidence on the effectiveness and the factors result in successful regenerative endodontic therapies in teeth with necrotic pulps and with incomplete root development. The study was conducted following the PRISMA Guidelines. There were no restrictions regarding search period. A comprehensive literature search was carried out in EMBASE, LILACS, PubMed, Cochrane, Scopus, and Google Scholar. A quality evaluation was conducted by using AMSTAR-2. A descriptive analysis of the included systematic reviews and meta-analysis were conducted.

Results

Thirteen descriptive systematic reviews and 7 meta-analyses were included. Three articles evidenced low methodological quality according to AMSTAR-2 tool. Overall success rates for the endodontic regeneration procedures ranged from 50% to 98% and the survival rates were between 94% and 100%. Pulp regeneration had a high success rate, evidenced by factors such as the resolution of symptoms, healing, increased root length, dentin thickening and recovery of sensitivity. Follow-up varied from 1 to 48 months for the original studies included in the systematic reviews and meta-analyses.

Conclusions

Endodontic practice offers the clinician a good treatment option in case of necrotic pulp with immature roots such as the endodontic regeneration, that is supported by high and moderate quality scientific literature.

Facilitating Reparative Dentin Formation Using Apigenin Local Delivery in the Exposed Pulp Cavity

Apigenin, a natural product belonging to the flavone class, affects various cell physiologies, such as cell signaling, inflammation, proliferation, migration, and protease production. In this study, apigenin was applied to mouse molar pulp after mechanically pulpal exposure to examine the detailed function of apigenin in regulating pulpal inflammation and tertiary dentin formation. In vitro cell cultivation using human dental pulp stem cells (hDPSCs) and in vivo mice model experiments were employed to examine the effect of apigenin in the pulp and dentin regeneration. In vitro cultivation of hDPSCs with apigenin treatment upregulated bone morphogenetic protein (BMP)- and osteogenesis-related signaling molecules such as BMP2, BMP4, BMP7, bone sialoprotein (BSP), runt-related transcription factor 2 (RUNX2), and osteocalcin (OCN) after 14 days. After apigenin local delivery in the mice pulpal cavity, histology and cellular physiology, such as the modulation of inflammation and differentiation, were examined using histology and immunostainings. Apigenin-treated specimens showed period-altered immunolocalization patterns of tumor necrosis factor (TNF)-α, myeloperoxidase (MPO), NESTIN, and transforming growth factor (TGF)-β1 at 3 and 5 days. Moreover, the apigenin-treated group showed a facilitated dentin-bridge formation with few irregular tubules after 42 days from pulpal cavity preparation. Micro-CT images confirmed obvious dentin-bridge structures in the apigenin-treated specimens compared with the control. Apigenin facilitated the reparative dentin formation through the modulation of inflammation and the activation of signaling regulations. Therefore, apigenin would be a potential therapeutic agent for regenerating dentin in exposed pulp caused by dental caries and traumatic injury.

Dental mesenchymal stromal/stem cells in different microenvironments— implications in regenerative therapy

Current research data reveal microenvironment as a significant modifier of physical functions, pathologic changes, as well as the therapeutic effects of stem cells. When comparing regeneration potential of various stem cell types used for cytotherapy and tissue engineering, mesenchymal stem cells (MSCs) are currently the most attractive cell source for bone and tooth regeneration due to their differentiation and immunomodulatory potential and lack of ethical issues associated with their use. The microenvironment of donors and recipients selected in cytotherapy plays a crucial role in regenerative potential of transplanted MSCs, indicating interactions of cells with their microenvironment indispensable in MSC-mediated bone and dental regeneration. Since a variety of MSC populations have been procured from different parts of the tooth and tooth-supporting tissues, MSCs of dental origin and their achievements in capacity to reconstitute various dental tissues have gained attention of many research groups over the years. This review discusses recent advances in comparative analyses of dental MSC regeneration potential with regards to their tissue origin and specific microenvironmental conditions, giving additional insight into the current clinical application of these cells.

Fabrication of Vascularized DPSC Constructs for Efficient Pulp Regeneration

Dental pulp regeneration is a promising approach to restore the vitality of necrotic teeth. We have previously reported the fabrication of scaffold-free cell constructs containing only dental pulp stem cells (DPSCs) and their ability to form pulp-like tissue in the pulpless tooth. However, the DPSC construct could not build pulp-like tissue with a full root length because it is difficult to induce blood vessels from a small root canal foramen. Therefore, we hypothesized that vascular structure could be preformed in the DPSC construct by employing endothelial differentiation capability of DPSCs, and vascularized constructs might facilitate dental pulp regeneration in the pulpless tooth. In this study, vascularized DPSC constructs were fabricated by inducing endothelial differentiation, and then we investigated the behavior of differentiated DPSCs, the internal structure of cell constructs, and their pulp regenerative ability in vivo. We observed that DPSCs positive for CD31 and von Willebrand factor were localized at the outer layer of constructs and formed a reticulated lumen structure. The cells constituting the outer layer of the construct expressed endothelial differentiation markers at higher levels than cells in the inner part. These results indicated that DPSCs in the outer layer differentiated into endothelial cells and formed vascular-like structures in the cell construct. Next, a vascularized DPSC construct was transplanted into the human pulpless tooth that was implanted into immunodeficient mice in the subcutaneous space. After 6 wk of implantation, the vascularized construct formed pulp-like tissues with higher density of human CD31-positive blood vessels when compared with specimens implanted with a DPSC construct without prevascularization. These results suggest that the vascular structure formed in the DPSC construct facilitated the blood supply and enhanced pulp regeneration. This study demonstrates that a vascularized DPSC construct is a prospective biomaterial as an implant for novel dental pulp regeneration.

Odontogenic gene expression profile of human dental pulp-derived cells under high glucose influence: a microarray analysis

Hyperglycemia, a major characteristic of diabetes, is considered to play a vital role in diabetic complications. High glucose levels have been found to inhibit the mineralization of dental pulp cells. However, gene expression associated with this phenomenon has not yet been reported. This is important for future dental therapeutic application.

OBJECTIVE

Our study aimed to investigate the effect of high glucose levels on mineralization of human dental pulp-derived cells (hDPCs) and identify the genes involved.

METHODOLOGY

hDPCs were cultured in mineralizing medium containing 25 or 5.5 mM D-glucose. On days 1 and 14, RNA was extracted and expression microarray performed. Then, differentially expressed genes (DEGs) were selected for further validation using the reverse transcription quantitative polymerase chain reaction (RT-qPCR) method. Cells were fixed and stained with alizarin red on day 21 to detect the formation of mineralized nodules, which was further quantified by acetic acid extraction.

RESULTS

Comparisons between high-glucose and low-glucose conditions showed that on day 1, there were 72 significantly up-regulated and 75 down-regulated genes in the high-glucose condition. Moreover, 115 significantly up- and 292 down-regulated genes were identified in the high-glucose condition on day 14. DEGs were enriched in different GO terms and pathways, such as biological and cellular processes, metabolic pathways, cytokine-cytokine receptor interaction and AGE-RAGE signaling pathways. RT-qPCR results confirmed the significant expression of pyruvate dehydrogenase kinase 3 (PDK3), cyclin-dependent kinase 8 (CDK8), activating transcription factor 3 (ATF3), fibulin-7 (Fbln-7), hyaluronan synthase 1 (HAS1), interleukin 4 receptor (IL-4R) and apolipoprotein C1 (ApoC1).

CONCLUSIONS

The high-glucose condition significantly inhibited the mineralization of hDPCs. DEGs were identified, and interestingly, HAS1 and Fbln-7 genes may be involved in the glucose inhibitory effect on hDPC mineralization.

The Role of microRNAs in Pulp Inflammation

The dental pulp can be affected by thermal, physical, chemical, and bacterial phenomena that stimulate the inflammatory response. The pulp tissue produces an immunological, cellular, and vascular reaction in an attempt to defend itself and resolve the affected tissue. The expression of different microRNAs during pulp inflammation has been previously documented. MicroRNAs (miRNAs) are endogenous small molecules involved in the transcription of genes that regulate the immune system and the inflammatory response. They are present in cellular and physiological functions, as well as in the pathogenesis of human diseases, becoming potential biomarkers for diagnosis, prognosis, monitoring, and safety. Previous studies have evidenced the different roles played by miRNAs in proinflammatory, anti-inflammatory, and immunological phenomena in the dental pulp, highlighting specific key functions of pulp pathology. This systematized review aims to provide an understanding of the role of the different microRNAs detected in the pulp and their effects on the expression of the different target genes that are involved during pulp inflammation.

Expression of nitric oxide synthases in rat odontoblasts and the role of nitric oxide in odontoblastic differentiation of rat dental papilla cells

As precursor cells of odontoblasts, dental papilla cells (DPCs) form the dentin-pulp complex during tooth development. Nitric oxide (NO) regulates the functions of multiple cells and organ tissues, including stem cell differentiation and bone formation. In this paper, we explored the involvement of NO in odontoblastic differentiation. We verified the expression of NO synthase (NOS) in rat odontoblasts by nicotinamide adenine dinucleotide phosphate-diaphorase (NADPH-d) staining and immunohistochemistry in vivo. The expression of all three NOS isoforms in rat DPCs was confirmed by quantitative reverse-transcription polymerase chain reaction (qRT-PCR), immunofluorescence, and western blotting in vitro. The expression of neuronal NOS and endothelial NOS was upregulated during the odontoblastic differentiation of DPCs. Inhibition of NOS function by NOS inhibitor l-N^G -monomethyl arginine (L-NMMA) resulted in reduced formation of mineralized nodules and expression of dentin sialophosphoprotein (DSPP) and dentin matrix protein (DMP1) during DPC differentiation. The NO donor S-nitroso-N-acetylpenicillamine (SNAP, 0.1, 1, 10, and 100 μM) promoted the viability of DPCs. Extracellular matrix mineralization and odontogenic markers expression were elevated by SNAP at low concentrations (0.1, 1, and 10 μM) and suppressed at high concentration (100 μM). Blocking the generation of cyclic guanosine monophosphate (cGMP) with 1H-(1,2,4)oxadiazolo-(4,3-a)quinoxalin-1-one (ODQ) abolished the positive influence of SNAP on the odontoblastic differentiation of DPCs. These findings demonstrate that NO regulates the odontoblastic differentiation of DPCs, thereby influencing dentin formation and tooth development.

Functional roles of fish collagen peptides on bone regeneration

Fish collagen peptides (FCP) derived from the skin, bones and scales are commercially used as a functional food or dietary supplement for hypertension and diabetes. However, there is limited evidence on the effects of FCP on the osteoblast function in contrast to evidence of the effects on wound healing, diabetes and bone regeneration, which have been obtained from animal studies. In this narrative review, we expound on the availability of FCP by basic research using osteoblasts. Low-concentration FCP upregulates the expression of osteoblast proliferation, differentiation and collagen modifying enzyme-related genes. Furthermore, it could accelerate matrix mineralization. FCP may have potential utility as a biomaterial to improve collagen quality and promote mineralization through the mitogen-activated protein kinase and Smad cascades. However, there are few clinical studies on bone regeneration in human subjects. It is desirable to be applied clinically through clinical study as soon as possible, based on the results from basic research.

The Role of Dendritic Cells during Physiological and Pathological Dentinogenesis

The dental pulp is a soft connective tissue of ectomesenchymal origin that harbors distinct cell populations, capable of interacting with each other to maintain the vitality of the tooth. After tooth injuries, a sequence of complex biological events takes place in the pulpal tissue to restore its homeostasis. The pulpal response begins with establishing an inflammatory reaction that leads to the formation of a matrix of reactionary or reparative dentin, according to the nature of the exogenous stimuli. Using several in vivo designs, antigen-presenting cells, including macrophages and dendritic cells (DCs), are identified in the pulpal tissue before tertiary dentin deposition under the afflicted area. However, the precise nature of this phenomenon and its relationship to inherent pulp cells are not yet clarified. This literature review aims to discuss the role of pulpal DCs and their relationship to progenitor/stem cells, odontoblasts or odontoblast-like cells, and other immunocompetent cells during physiological and pathological dentinogenesis. The concept of “dentin-pulp immunology” is proposed for understanding the crosstalk among these cell types after tooth injuries, and the possibility of immune-based therapies is introduced to accelerate pulpal healing after exogenous stimuli.

Cytotoxicity and effects of curcumin and cinnamaldehyde hybrids on biofilms of oral pathogens

The objective of the study was to evaluate the cytotoxicity and effect of curcumin-cinnamaldehyde hybrids (CCHs) on the biofilm of oral pathogens. Of the 18 hybrids tested, nine had an inhibitory effect on at least one of the bacterial species tested, with minimal inhibitory and bactericidal concentrations ranging from 9 to 625 μg ml^-1. CCH 7 promoted a potent inhibitory effect against all the bacterial species tested and better compatibility than chlorhexidine (CHX). CCH 7 also presented a similar or improved effect over that of CHX, causing a reduction in bacterial metabolism and viability in single and dual-species biofilms. CCH 7 reduced by 86% and 34% the viability of multispecies biofilms formed by collection and clinical strains. It can be concluded that CCH 7 was cytocompatible at the minimal inhibitory concentration, presented anti-biofilm action against oral pathogens, and could act as an antimicrobial agent for application in endodontics.

Doxycycline-Loaded Nitric Oxide-Releasing Nanomatrix Gel in Replanted Rat Molar on Pulp Regeneration

The aim of the present study was to evaluate the effect of doxycycline-loaded NO-releasing nanomatrix gel on pulp regeneration in replantation of avulsed rat teeth. A total of 28 maxillary first molars extracted from rats were replanted. The rats were divided into two groups based on the use of root surface treatment: doxycycline-loaded NO-releasing nanomatrix group and no treatment. Eight weeks after replantation, the rats were sacrificed, and the teeth were evaluated using histomorphometric analysis. On histomorphometric analysis, the NO-releasing nanomatrix group demonstrated a significantly lower grade of pulp inflammation (1.00 ± 1.11, mean ± standard deviation) compared to the no treatment group (2.21 ± 1.25, p = 0.014). NO-releasing nanomatrix group showed a significantly higher grade of pulp regeneration (2.57 ± 0.85, p = 0.012) and significantly lower grade of pulp inflammation (1.00 ± 0.68, p = 0.025) compared to the no treatment group. In conclusion, NO-releasing nanomatrix gel improved pulp regeneration of replanted teeth, though the sample size of this study was rather small. Within the limits of this study, NO-releasing nanomatrix gel can provide more favorable pulpal regeneration despite replantation.

SHED aggregate exosomes shuttled miR-26a promote angiogenesis in pulp regeneration via TGF-β/SMAD2/3 signalling

OBJECTIVES

Pulp regeneration brings big challenges for clinicians, and vascularization is considered as its determining factor. We previously accomplished pulp regeneration with autologous stem cells from deciduous teeth (SHED) aggregates implantation in teenager patients, however, the underlying mechanism needs to be clarified for regenerating pulp in adults. Serving as an important effector of mesenchymal stem cells (MSCs), exosomes have been reported to promote angiogenesis and tissue regeneration effectively. Here, we aimed to investigate the role of SHED aggregate-derived exosomes (SA-Exo) in the angiogenesis of pulp regeneration.

MATERIALS AND METHODS

We extracted exosomes from SHED aggregates and utilized them in the pulp regeneration animal model. The pro-angiogenetic effects of SA-Exo on SHED and human umbilical vein endothelial cells (HUVECs) were evaluated. The related mechanisms were further investigated.

RESULTS

We firstly found that SA-Exo significantly improved pulp tissue regeneration and angiogenesis in vivo. Next, we found that SA-Exo promoted SHED endothelial differentiation and enhanced the angiogenic ability of HUVECs, as indicated by the in vitro tube formation assay. Mechanistically, miR-26a, which is enriched in SA-Exo, improved angiogenesis both in SHED and HUVECs via regulating TGF-β/SMAD2/3 signalling.

CONCLUSIONS

In summary, these data reveal that SA-Exo shuttled miR-26a promotes angiogenesis via TGF-β/SMAD2/3 signalling contributing to SHED aggregate-based pulp tissue regeneration. These novel insights into SA-Exo may facilitate the development of new strategies for pulp regeneration.

Alleviation of Oxidative Stress in Dental Pulp Cells Following 4-Hexylresorcinol Administration in a Rat Model

Damaged dental pulp undergoes oxidative stress and 4-hexylresorcinol (4HR) is a well-known antioxidant. In this study, we aimed to evaluate the therapeutic effects of a 4HR ointment on damaged dental pulp. Pulp cells from rat mandibular incisor were cultured and treated with 4HR or resveratrol (1–100 μM). These treatments (10–100 μM) exerted a protective effect during subsequent hydrogen peroxide treatments. The total antioxidant capacity and glutathione peroxidase activity were significantly increased following 4HR or resveratrol treatment (p < 0.05), while the expression levels of TNF-α and IL1β were decreased following the exposure to 4HR pre-treatment in an in vitro model. Additionally, the application of 4HR ointment in an exposed dental pulp model significantly reduced the expression of TNF-α and IL1β (p < 0.05). Conclusively, 4HR exerted protective effects against oxidative stress in dental pulp tissues through downregulating TNF-α and IL1β.

The Role of Small Extracellular Vesicles Derived from Lipopolysaccharide-preconditioned Human Dental Pulp Stem Cells in Dental Pulp Regeneration

INTRODUCTION

Regenerative endodontics has created a desirable shift in the treatment paradigm despite current limitations of regenerative outcomes. Mesenchymal stem cells (MSCs) facilitate tissue regeneration and repair in a mild inflammatory environment. Small extracellular vesicles (sEVs) derived from MSCs play an imperative role in the paracrine modulation of regenerative responses modulated by MSCs. However, it remains unknown whether MSCs enhance dental pulp regeneration or whether this enhancement is mediated by sEVs in a mild inflammatory environment. The present study aimed to elucidate the effects of sEVs originated from lipopolysaccharide (LPS)-preconditioned human dental pulp stem cells (hDPSCs) on dental pulp regeneration.

METHODS

All sEVs were isolated from hDPSCs cultured with or without LPS (ie, N-sEVs and L-sEVs, respectively). The effect of N-sEVs and L-sEVs on proliferation, migration, angiogenesis, and differentiation of rat bone marrow MSCs was identified in vitro. Moreover, N-sEVs or L-sEVs were implanted into rat pulpless root canal models, and the regenerated tissue in root canals was assessed via hematoxylin-eosin staining, Masson staining, and immunohistochemistry after 30 days of transplantation.

RESULTS

Both N-sEVs and L-sEVs could modulate BMSC proliferation, migration, angiogenesis, and differentiation. Both kinds of sEVs enhanced the structure of the regenerated tissue closer to that of a normal dental pulp in vivo. L-sEVs had a more significant effect than N-sEVs.

CONCLUSIONS

sEVs released by hDPSCs in a mild inflammatory microenvironment are capable of facilitating the regeneration of dental pulp through functional healing instead of scar healing, which has potential applications in regenerative endodontics.

Distinct Expression Patterns of Cxcl12 in Mesenchymal Stem Cell Niches of Intact and Injured Rodent Teeth

Specific stem cell populations within dental mesenchymal tissues guarantee tooth homeostasis and regeneration throughout life. The decision between renewal and differentiation of stem cells is greatly influenced by interactions with stromal cells and extracellular matrix molecules that form the tissue specific stem cell niches. The Cxcl12 chemokine is a general marker of stromal cells and plays fundamental roles in the maintenance, mobilization and migration of stem cells. The aim of this study was to exploit Cxcl12-GFP transgenic mice to study the expression patterns of Cxcl12 in putative dental niches of intact and injured teeth. We showed that endothelial and stromal cells expressed Cxcl12 in the dental pulp tissue of both intact molars and incisors. Isolated non-endothelial Cxcl12⁺ dental pulp cells cultured in different conditions in vitro exhibited expression of both adipogenic and osteogenic markers, thus suggesting that these cells possess multipotent fates. Taken together, our results show that Cxcl12 is widely expressed in intact and injured teeth and highlight its importance as a key component of the various dental mesenchymal stem cell niches.

Melatonin Treatment Alters Biological and Immunomodulatory Properties of Human Dental Pulp Mesenchymal Stem Cells via Augmented Transforming Growth Factor Beta Secretion

INTRODUCTION

Melatonin is an endogenous neurohormone with well-reported anti-inflammatory and antioxidant properties, but the direct biological and immunomodulatory effects of melatonin on human dental pulp stem cells (hDPSCs) has not been fully elucidated. The aim of this study was to evaluate the influence of melatonin on the cytocompatibility, proliferation, cell migration, odontogenic differentiation, mineralized nodule formation, and immunomodulatory properties of hDPSCs.

METHODS

To address the melatonin biological effects on hDPSCs, the cytocompatibility, proliferation, cell migration, odontogenic differentiation, mineralized nodule formation, and immunomodulatory properties of hDPSCs after melatonin treatment were evaluated. The statistical differences were evaluated using 1-way analysis of variance with the Tukey multiple comparison test.

RESULTS

We found that melatonin did not alter hDPSC immunophenotype or cell viability, even at the highest concentrations used. However, using intermediate melatonin concentrations (10-300 μmol/L), a significantly higher proliferation rate (P < .05 and P < .01) and migration of hDPSCs (P < .01) were observed. Importantly, melatonin treatment (100 μmol/L) significantly increased the secretion of the anti-inflammatory cytokine transforming growth factor beta (P < .05 and P < .01) and provoked a more robust antiproliferative effect on mitogen-stimulated T cells (P < .05). Finally, and unlike previous results found with mesenchymal stem cells from other sources, melatonin fails to induce or accelerate the spontaneous osteogenic differentiation of hDPSCs.

CONCLUSIONS

Together, these findings provide key data on the bioactivity of melatonin and its effects on hPDSC biological and immunomodulatory properties.

Characterization of Odontogenic Differentiation from Human Dental Pulp Stem Cells Using TMT-Based Proteomic Analysis

Background

The repair of dental pulp injury relies on the odontogenic differentiation of dental pulp stem cells (DPSCs). To better understand the odontogenic differentiation of DPSCs and identify proteins involved in this process, tandem mass tags (TMTs) coupled with liquid chromatography-tandem mass spectrometry (LC-MS/MS) were applied to compare the proteomic profiles of induced and control DPSCs.

Methods

The proteins expressed during osteogenic differentiation of human DPSCs were profiled using the TMT method combined with LC-MS/MS analysis. The identified proteins were subjected to Gene Ontology (GO) and Kyoto Encyclopedia of Genes and Genomes (KEGG) pathway analyses. Then, a protein-protein interaction (PPI) network was constructed. Two selected proteins were confirmed by western blotting (WB) analysis.

Results

A total of 223 proteins that were differentially expressed were identified. Among them, 152 proteins were significantly upregulated and 71 were downregulated in the odontogenic differentiation group compared with the control group. On the basis of biological processes in GO, the identified proteins were mainly involved in cellular processes, metabolic processes, and biological regulation, which are connected with the signaling pathways highlighted by KEGG pathway analysis. PPI networks showed that most of the differentially expressed proteins were implicated in physical or functional interaction. The protein expression levels of FBN1 and TGF-β2 validated by WB were consistent with the proteomic analysis.

Conclusions

This is the first proteomic analysis of human DPSC odontogenesis using a TMT method. We identified many new differentially expressed proteins that are potential targets for pulp-dentin complex regeneration and repair.

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.

The Combination of Diode Laser and Ozonated Water in the Treatment of Complicated Pulp Gangrene

The study aimed to investigate the effects of endodontic space decontamination using a laser combined with ozonated water in the therapy of complicated pulp gangrene. The subject of this in vivo study was a 12-year-old patient diagnosed with extensive periapical periodontitis on the mandibular right first molar. Biological samples were initially collected to identify the active pathogen—Enterococcus faecalis, then the nonsurgical endodontic treatment was performed in a single visit, according to the active disinfection guidelines of the identified pathogen. Two-month postoperative, clinical and radiological examination revealed a complete healing of the periapical lesion. The correct diagnosis of this endodontic–periodontal pathology, and the unconventional treatment of the complex system of infected root canals, allowed a favorable treatment result without any surgical intervention. This unconventional approach, which combines a laser technique with ozonated water, allows for predictable results in periapical lesion treatment.

Comparative Surface Morphology, Chemical Composition, and Cytocompatibility of Bio-C Repair, Biodentine, and ProRoot MTA on hDPCs

Biocompatibility is an essential property for any vital pulp material that may interact with the dental pulp tissues. Accordingly, this study aimed to compare the chemical composition and ultrastructural morphology of Biodentine (Septodont, Saint Maur-des-Fosses, France), ProRoot MTA (Dentsply Tulsa Dental Specialties, Johnson City, TN, USA), and Bio-C Repair (Angelus, Londrina, PR, Brazil), as well as their biological effects on human dental pulp cells. Chemical element characterization of the materials was undertaken using scanning electron microscopy and energy dispersive X-ray analysis (SEM-EDX). The cytotoxicity was assessed by analyzing the cell viability (MTT assay), cell morphology (immunofluorescence assay), and cell attachment (flow cytometry assay). The results were statistically analyzed using ANOVA and Tukey’s test (p < 0.05). EDX revealed that ProRoot MTA and Biodentine were mostly composed of calcium, carbon, and oxygen (among others), whereas Bio-C Repair evidenced a low concentration of calcium and the highest concentration of zirconium. SEM showed adequate attachment of human dental pulp cells (hDPCS) to vital pulp materials and cytoskeletal alterations were not observed in the presence of material eluates. Remarkably, the undiluted Biodentine group showed higher viability than the control group cells (without eluates) at 24 h, 48 h, and 72 h (p < 0.001). Based on the evidence derived from an in vitro cellular study, it was concluded that Bio-C Repair showed excellent cytocompatibility that was similar to Biodentine and ProRoot MTA.

Performance of a Biodegradable Composite with Hydroxyapatite as a Scaffold in Pulp Tissue Repair

Vital pulp therapy is an important endodontic treatment. Strategies using growth factors and biological molecules are effective in developing pulp capping materials based on wound healing by the dentin-pulp complex. Our group developed biodegradable viscoelastic polymer materials for tissue-engineered medical devices. The polymer contents help overcome the poor fracture toughness of hydroxyapatite (HAp)-facilitated osteogenic differentiation of pulp cells. However, the composition of this novel polymer remained unclear. This study evaluated a novel polymer composite, P(CL-co-DLLA) and HAp, as a direct pulp capping carrier for biological molecules. The biocompatibility of the novel polymer composite was evaluated by determining the cytotoxicity and proliferation of human dental stem cells in vitro. The novel polymer composite with BMP-2, which reportedly induced tertiary dentin, was tested as a direct pulp capping material in a rat model. Cytotoxicity and proliferation assays revealed that the biocompatibility of the novel polymer composite was similar to that of the control. The novel polymer composite with BMP-2-induced tertiary dentin, similar to hydraulic calcium-silicate cement, in the direct pulp capping model. The BMP-2 composite upregulated wound healing-related gene expression compared to the novel polymer composite alone. Therefore, we suggest that novel polymer composites could be effective carriers for pulp capping.