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

Cellular dynamics and signalling mechanisms in dentine repair: A narrative review

BACKGROUND

Bioactive molecules have gained significant attention in regenerative medicine due to their ability to boost the reparative properties of stem cells, including those in the dental pulp. This narrative review aims to deepen our understanding of the dynamics of bioactive molecules in the dental pulp and their role in enhancing hard tissue reparative processes.

OBJECTIVES

(i) To discuss the role of different cells and the critical pathways involved in dentine formation through direct (reparative) or indirect (infection control and immunomodulatory) mechanisms. (ii) To highlight how innovative therapeutic strategies could be employed to target key molecules for successful dentine repair and regeneration.

METHODS

The review encompassed all years up to the search period. Databases such as PubMed, Scopus and Medline were utilized to gather relevant studies. The search strategy involved specific signalling molecules such as Transforming growth factor-β1 (TGF-β), Bone Morphogenetic Proteins (BMP), Small Integrin Binding Ligand N-linked Glycoproteins (SIBLING) and growth factors. Cell types including odontoblasts, fibroblasts, immune cells and dental pulp stem cells (DPSCs) were of interest. Additionally, signalling pathways like Wnt, Notch, Shh, amongst others, were investigated for their roles in repair mechanisms. Key terms were combined using Boolean operators [Cell type] AND [signalling molecules] AND/OR [dentine], [Cell type] AND/OR [signalling pathways] AND/OR [dentine] to include studies addressing the interaction of these components in enhancing repair processes.

DISCUSSION

Key molecules such as TGF-β1, BMP and SIBLING proteins effectively enhance the dentine reparative response, whilst other molecules such as complement proteins and antimicrobial peptides primarily activate immune cells and facilitate pathogen clearance to promote the regenerative capabilities of DPSCs. This well-orchestrated interaction emphasizes the need to investigate the effects of these molecules on all cells within the dental pulp. Morphogenic signalling molecules such as BMP-2, -4 and -7, and Wnt show temporal, yet significant regenerative properties, whilst Shh and Notch present inconsistent effects on dentine regeneration, and a consensus on their roles and properties in dentine repair has yet to be reached.

CONCLUSIONS

This review highlights the critical role of bioactive molecules in dentine repair to guide the development of next-generation bioinspired therapeutics for vital pulp therapy.

How epigenetics and miRNA affect gene expression in dental pulp inflammation: A narrative review

BACKGROUND

Pulpitis, an inflammatory condition of the dental pulp, typically arises due to caries. It can remain asymptomatic for extended periods, complicating its diagnosis. The inflammatory response induced by bacterial invasion encompasses both cell-mediated and humoural immunity, accompanied by neural and vascular changes. The primary aim of inflammation is to eradicate invading pathogens from the pulp. However, failure to eliminate pathogens may result in necrosis of the pulp. Before direct bacterial contact with cells occurs, the pulp initiates protective responses like the formation of tertiary dentine. The interaction between bacterial surface proteins and specific receptors on pulp cells, primarily odontoblasts and dendritic cells, activates intracellular signalling pathways. These cascades, mediated by transcription factors, regulate gene expression and subsequent protein synthesis, thereby modulating the inflammatory response. In addition to proinflammatory and anti-inflammatory mediators, microRNAs and epigenetic modifications play a key role in gene expression in dental pulp. Epigenetic changes including DNA methylation and histone modifications can occur within the pulp.

OBJECTIVES

Dental pulp inflammation represents a highly intricate network of signalling pathways, messenger molecules and cellular interactions. The ongoing research continuously expands our understanding of these processes. The objective of this review is to investigate mechanisms of dental pulp inflammation, concentrating on the regulation of gene expression. This consists of transcription factors, microRNAs, epigenetic modifications and mitochondrial DNA, among others. This review aims to highlight recent findings about biomolecular and epigenetical mechanisms of pulpitis as well as their role in gene expression.

CONCLUSIONS

Pulp inflammation is a complex series of events happening on a molecular and cellular level. Even though the pulp tissue is hardly examined in vivo, laboratory studies offer great new insights and potential for our understanding of its inflammatory mechanisms. Recognition of bacterial components by pulp cells is the initiator of overlapping signalling pathways that will eventually lead to gene activation or repression. Specific genes might be activated, resulting in the production of messenger molecules like cytokines and chemokines. Trending topics of medicine like microRNA and epigenetics are also discussed in the context of dentistry. This knowledge could be used to develop new therapeutics in endodontics.

Environmental stimuli-responsive hydrogels in endodontics: Advances and perspectives

Stimuli-responsive hydrogels are smart and functional materials that respond to various environmental stimuli, including temperature, light, magnetic field, pH, redox, enzymes and glucose. This responsiveness allows for the controlled release of therapeutic agents encapsulated within the hydrogels, enhancing treatment precision, improving therapeutic outcomes and minimizing side effects. Such hydrogels show great potential in root canal disinfection, management of dental pulp inflammation and pulp regeneration, making them promising candidates for more personalized and effective endodontic treatments. This article provides an overview of the latest advancements in the design and application of stimuli-responsive hydrogels in endodontics, emphasizing their potential to revolutionize endodontic treatments. It also addresses current challenges and explores future directions in the field, aiming to inspire and motivate researchers to further engage in or intensify their efforts within this promising area of research.

FoxO1 mediates odontoblast differentiation of hDPSCs via B cell-derived ANGPTL1 in dental caries: A laboratory investigation

AIM

Clinical and in vitro evidence indicates that chronic inflammatory responses initiated by dental caries can persist in the dental pulp even after treatment, necessitating the formation of reparative dentin to restore tissue homeostasis and health. Human dental pulp stem cells (hDPSCs) serve as crucial precursors in this reparative process. This study explores the role of B cells and their secreted factor, Angiopoietin Like 1 (ANGPTL1), in promoting hDPSCs differentiation into odontoblasts under carious conditions, with a particular focus on the activation of Forkhead box O1 (FoxO1).

METHODOLOGY

Single-cell RNA sequencing (scRNA-Seq) data from the GEO database were analysed to explore cellular interactions and molecular mechanisms in dental pulp. Immunofluorescence staining was used to investigate the expression patterns of B cells or hDPSCs in dental pulp and hydroxyapatite/tricalcium phosphate (HA/TCP) scaffolds. The expression levels of ANGPTL1 were quantified using enzyme-linked immunosorbent assay (ELISA). Odontoblast differentiation capacity was assessed by alkaline phosphatase activity, alizarin red S staining, and western blotting analysis. hDPSCs were overexpressed or knocked down FoxO1 with lentiviruses. The regulatory interaction between FoxO1 and the DSPP promoter was evaluated through dual-luciferase reporter assay and chromatin immunoprecipitation assay. Statistical analyses were conducted using Student's t-test or one-way analysis of variance (anova) with a p-value of <.05 considered statistically significant.

RESULTS

scRNA-Seq data indicated a significant increase in B cells and ANGPTL1 expression in carious dental pulp. Functional analyses confirmed that ANGPTL1 secreted by B cells activated FoxO1 expression in hDPSCs, enhancing their differentiation into odontoblast-like cells. Blocking ANGPTL1 signalling with a specific antibody reduced FoxO1 expression, indicating a regulatory link between ANGPTL1 and FoxO1. Overexpression of FoxO1 in hDPSCs promoted their differentiation into odontoblasts and facilitated mineralized matrix formation. Mechanistic studies revealed that FoxO1 directly binds to the DSPP promoter, thereby inducing its expression.

CONCLUSIONS

Our study reveals a novel mechanism in which ANGPTL1 secreted by B cells in a carious environment promotes the odontoblast differentiation of hDPSCs by upregulating FoxO1. This finding highlights a potential therapeutic target for enhancing dental pulp repair and regeneration.

Healing with Love: Oxytocin Accelerates Oral Ulcer Recovery by Reducing Inflammation

Background: Oral ulcerative mucositis (OUM) is a painful, inflammatory mucosa lesion that impairs quality of life. Despite available treatments, effective agents that promote faster healing and modulate inflammation are still needed. Oxytocin (OT), a neuropeptide with anti-inflammatory and antioxidant properties, may aid wound healing by regulating the remodeling of the extracellular matrix (ECM). This study investigates the effects of OT on oral ulcer healing in rats, focusing on its modulation of the MMP-2/TIMP-2 pathway. Methods: Acetic acid 70% was used as the oral mucosal ulcer inducer. Thirty-six Wistar albino rats were divided into control, oral ulcer + saline, and oral ulcer + OT (intraperitoneally for 15 days) groups. Histopathological, biochemical, and molecular analyses were performed. Buccal mucosa tissue was examined for TNF-α, TIMP-2, and MMP-2 levels via ELISA, while oxidative stress markers and pentraxin-3 (PTX3) were also assessed. Results: OT significantly preserved epithelial integrity and reduced fibrosis compared to the saline group (p < 0.001). TNF-α, MMP-2, PTX3, and malondialdehyde levels were significantly lower, while TIMP-2 levels were elevated in the OT-treated group (p < 0.01). Histopathological analysis confirmed reduced inflammation and enhanced tissue organization. Conclusions: OT accelerates oral ulcer healing by modulating inflammation, oxidative stress, and ECM remodeling via the MMP-2/TIMP-2 pathway. These findings highlight its potential as a therapeutic agent for managing mucosal injuries. Further clinical studies are warranted.

DNMTi@ZIF-8 Enhances Biomimetic Pulp Regeneration via Epigenetic Regulation

Regenerating the functional dentin-pulp complex remains a significant challenge in endodontics. Conventional regenerative endodontic therapies often result in the formation of non-pulp-like tissue due to the uncontrolled induction of stem cells and cytokines. Mimicking developmental processes to promote regeneration represents a promising yet challenging approach in regenerative medicine. This study aimed to develop a biomimetic regenerative therapy that integrates a DNMTi@ZIF-8 nanoplatform with dental pulp stem cell (DPSC) spheroids to effectively regenerate the dentin-pulp complex. First, a progressive reduction in 5-methylcytosine content was revealed to be a core signal in the odontogenic differentiation process. Based on this discovery, DNA methyltransferase inhibitors (DNMTi) were further used to simulate this regulatory process. The results showed that DNMTi not only significantly promoted odontogenic differentiation but also inhibited the angiogenesis process. To address this dual effect, in situ synthesized zeolitic imidazolate framework-8 (ZIF-8) was used for the delivery of DNMTi. This DNMTi@ZIF-8 system not only prolonged drug activity but also enhanced angiogenesis-promoting efficacy by activating the PI3K-AKT signaling pathway through the sustained release of zinc ions, assessed via angiogenic assays including scratch assays, tube formation assay, and chick chorioallantoic membrane assay. When integrated with DPSC spheroids engineered via agarose microwells, analyzed through odontogenic differentiation assays, this system demonstrated significantly enhanced odontogenic differentiation capabilities. Moreover, the introduced biomimetic regenerative therapy successfully regenerated the dentin-pulp complex in a semi-orthotopic in vivo model. This biomimetic developmental approach not only addresses critical gaps in dental tissue engineering but also highlights a new direction for treating pulp and periapical diseases, underscoring its broader implications in regenerative medicine.

Role and mechanisms of histone methylation in osteogenic/odontogenic differentiation of dental mesenchymal stem cells

Dental mesenchymal stem cells (DMSCs) are pivotal for tooth development and periodontal tissue health and play an important role in tissue engineering and regenerative medicine because of their multidirectional differentiation potential and self-renewal ability. The cellular microenvironment regulates the fate of stem cells and can be modified using various optimization techniques. These methods can influence the cellular microenvironment, activate disparate signaling pathways, and induce different biological effects. "Epigenetic regulation" refers to the process of influencing gene expression and regulating cell fate without altering DNA sequences, such as histone methylation. Histone methylation modifications regulate pivotal transcription factors governing DMSCs differentiation into osteo-/odontogenic lineages. The most important sites of histone methylation in tooth organization were found to be H3K4, H3K9, and H3K27. Histone methylation affects gene expression and regulates stem cell differentiation by maintaining a delicate balance between major trimethylation sites, generating distinct chromatin structures associated with specific downstream transcriptional states. Several crucial signaling pathways associated with osteogenic differentiation are susceptible to modulation via histone methylation modifications. A deeper understanding of the regulatory mechanisms governing histone methylation modifications in osteo-/odontogenic differentiation and immune-inflammatory responses of DMSCs will facilitate further investigation of the epigenetic regulation of histone methylation in DMSC-mediated tissue regeneration and inflammation. Here is a concise overview of the pivotal functions of epigenetic histone methylation at H3K4, H3K9, and H3K27 in the regulation of osteo-/odontogenic differentiation and renewal of DMSCs in both non-inflammatory and inflammatory microenvironments. This review summarizes the current research on these processes in the context of tissue regeneration and therapeutic interventions.

Varghese R, Gupta NK, Choubey N, Dubey A, Priya S. In-vivo analysis of visible light cure calcium hydroxide, mineral trioxide aggregate and platelet-rich fibrin with and without laser therapy for direct pulp capping

The clinical and radiographic outcomes of direct pulp capping using visible light cure calcium hydroxide, Mineral Trioxide Aggregate, and Platelet-Rich Fibrin, with and without pre-treatment with a low-level diode laser is of interest to dentist. One hundred and twenty patients (18-48 years) with accidental minimal pulp exposures less than 1 mm2 were randomized into two primary groups: laser pre-treatment and no laser pre-treatment, each further divided into three sub-groups based on the capping material. Clinical and radiographic assessments were conducted at 7th day, 1st, 6th and 12th months. The combination of low-level diode laser and mineral trioxide aggregate with platelet-rich fibrin demonstrated superior clinical outcomes compared to other groups. Radiographic analysis showed significant differences in dentin bridge thickness among groups. While all tested materials exhibited promising results, further research is necessary to optimize treatment protocols and ensure long-term clinical success with a specific focus on dentin bridge formation and the potential influence of laser pre-treatment.

A carbon dot nanozyme hydrogel enhances pulp regeneration activity by regulating oxidative stress in dental pulpitis

Preserving pulp viability and promoting pulp regeneration in pulpitis have attracted widespread attention. Restricted by the oxidative stress microenvironment of dental pulpitis, excessive reactive oxygen and nitrogen species (RONS) trigger uncontrolled inflammation and exacerbate pulp tissue destruction. However, modulating redox homeostasis in inflamed pulp tissue to promote pulp regeneration remains a great challenge. Herein, this work proposes an effective antioxidative system (C-NZ/GelMA) consisting of carbon dot nanozymes (C-NZ) with gelatin methacryloyl (GelMA) to modulate the pulpitis microenvironment for dental pulp regeneration by utilizing the antioxidant properties of C-NZ and the mechanical support of an injectable GelMA hydrogel. This system effectively scavenges RONS to normalize intracellular redox homeostasis, relieving oxidative stress damage. Impressively, it can dramatically enhance the polarization of regenerative M2 macrophages. This study revealed that the C-NZ/GelMA hydrogel promoted pulp regeneration and dentin repair through its outstanding antioxidant, antiapoptotic, and anti-inflammatory effects, suggesting that the C-NZ/GelMA hydrogel is highly valuable for pulpitis treatment.

A ROS-responsive hydrogel incorporated with dental follicle stem cell-derived small extracellular vesicles promotes dental pulp repair by ameliorating oxidative stress

Pulpitis, an inflammatory disease of dental pulp tissues, ultimately results in the loss of pulp defense properties. Existing clinical modalities cannot effectively promote inflamed pulp repair. Oxidative stress is a major obstacle inhibiting pulp repair. Due to their powerful antioxidative capacity, mesenchymal stem cell-derived small extracellular vesicles (MSC-sEVs) exhibit potential for treating oxidative stress-related disorders. However, whether MSC-sEVs shield dental pulp tissues from oxidative damage is largely unknown. Here, we showed that dental follicle stem cell-derived sEVs (DFSC-sEVs) have antioxidative and prohealing effects on a rat LPS-induced pulpitis model by enhancing the survival, proliferation and odontogenesis of H2O2-injured dental pulp stem cells (DPSCs). Additionally, DFSC-sEVs restored the oxidative/antioxidative balance in DPSC mitochondria and had comparable effects on ameliorating mitochondrial dysfunction with the mitochondrion-targeted antioxidant Mito-Tempo. To improve the efficacy of DFSC-sEVs, we fabricated an intelligent and injectable hydrogel to release DFSC-sEVs by combining sodium alginate (SA) and the ROS sensor RhB-AC. The newly formed SA-RhB hydrogel efficiently encapsulates DFSC-sEVs and exhibits controlled release of DFSC-sEVs in a HClO/ClO- concentration-dependent manner, providing a synergistic antioxidant effect with DFSC-sEVs. These results suggest that DFSC-sEVs-loaded SA-RhB is a promising minimally invasive treatment for pulpitis by enhancing tissue repair in the pulp wound microenvironment.

Understanding the bio-crystallization: An insight to therapeutic relevance

In the realm of biomedical engineering and materials science, the synthesis of biomaterials plays a pivotal role in advancing therapeutic strategies for regeneration of tissues. The deliberate control of crystallization processes in biomaterial synthesis has emerged as a key avenue for tailoring the properties of these materials, enabling the design of innovative solutions for a wide array of medical applications. This review delves into the interplay between controlled crystallization and biomaterial synthesis, exploring its multifaceted applications in the therapeutic domains. The investigation encompasses a wide spectrum of matrices, ranging from small molecules to large biomolecules, highlighting their unique contributions in modulating crystallization processes. Furthermore, the review critically assesses the analytical techniques and methodologies employed to probe and characterize the depths of crystallization dynamics. Advanced imaging, spectroscopic, and computational tools are discussed in the context of unraveling the intricate mechanisms governing nucleation and crystallization processes within the organic matrix. Finally we delve in the applications of such advance material in therapeutics of hard and soft tissues.

Advances and challenges in regenerative dentistry: A systematic review of calcium phosphate and silicate-based materials on human dental pulp stem cells

Conventional dentistry faces limitations in preserving tooth health due to the finite lifespan of restorative materials. Regenerative dentistry, utilizing stem cells and bioactive materials, offers a promising approach for regenerating dental tissues. Human dental pulp stem cells (hDPSCs) and bioactive materials like calcium phosphate (CaP) and silicate-based materials have shown potential for dental tissue regeneration. This systematic review aims to investigate the effects of CaP and silicate-based materials on hDPSCs through in vitro studies published since 2015. Following the PRISMA guidelines, a comprehensive search strategy was implemented in PubMed MedLine, Cochrane, and ScienceDirect databases. Eligibility criteria were established using the PICOS scheme. Data extraction and risk of bias (RoB) assessment were conducted, with the included studies assessed for bias using the Office of Health and Translation (OHAT) RoB tool. The research has been registered at OSF Registries. Ten in vitro studies met the eligibility criteria out of 1088 initial studies. Methodological heterogeneity and the use of self-synthesized biomaterials with limited generalizability were observed in the included study. The findings highlight the positive effect of CaP and silicate-based materials on hDPSCs viability, adhesion, migration, proliferation, and differentiation. While the overall RoB assessment indicated satisfactory credibility of the reviewed studies, the limited number of studies and methodological heterogeneity pose challenges for quantitative research. In conclusion, this systematic review provides valuable insights into the effects of CaP and silicate-based materials on hDPSCs. Further research is awaited to enhance our understanding and optimize regenerative dental treatments using bioactive materials and hDPSCs, which promise to improve patient outcomes.

Approaches to vital pulp therapies

Tooth decay, which leads to pulpal inflammation due to the pulp's response to bacterial components and byproducts is the most common infectious disease. The main goals of clinical management are to eliminate sources of infection, to facilitate healing by regulating inflammation indental tissue, and to replace lost tissues. A variety of novel approaches from tissue engineering based on stem cells, bioactive molecules, and extracellular matrix-like scaffold structures to therapeutic applications, or a combination of all these are present in the literature. Shortcomings of existing conventional materials for pulp capping and the novel approches aiming to preserve pulp vitality highligted the need for developing new targeted dental materials. This review looks at the novel approches for vital pulp treatments after briefly addresing the conventional vital pulp treatment as well as the regenerative and self defense capabilities of the pulp. A narrative review focusing on the current and future approaches for pulp preservation was performed after surveying the relevant papers on vital pulp therapies including pulp capping, pulpotomy, and potential approaches for facilitating dentin-pulp complex regeneration in PubMed, Medline, and Scopus databases.

Multifunctional Lithium-Doped Mesoporous Nanoparticles for Effective Dentin Regeneration in vivo

Introduction

Effective infection control without irritating the pulp tissue is the key to successful vital pulp therapy. Developing a novel antibacterial biomaterial that promotes dentin regeneration for pulp capping is thus a promising strategy for enhancing vital pulp therapy.

Methods

Lithium-doped mesoporous nanoparticles (Li-MNPs) were synthesized using an alkali-catalyzed sol-gel method. The particle size, elemental distribution, surface morphology, pore structure, and ion release from Li-MNPs were measured. Human dental pulp stem cells (hDPSCs) and Streptococcus mutans (S. mutans) were used to evaluate the biological effects of Li-MNPs. In addition, a dental pulp exposure mouse model was used to evaluate the regenerative effects of Li-MNPs.

Results

Li-MNPs had a larger surface area (221.18 m2/g), a larger pore volume (0.25 cm3/g), and a smaller particle size (520.92 ± 35.21 nm) than MNPs. The in vitro investigation demonstrated that Li-MNPs greatly enhanced the biomineralization and odontogenic differentiation of hDPSCs through the Wnt/β-catenin signaling pathway. Li-MNPs showed a strong antibacterial effect on S. mutans. As expected, Li-MNPs significantly promoted dentin regeneration in situ and in vivo.

Conclusion

Li-MNPs promoted dentin regeneration and inhibited S. mutans growth, implying a possible application as a pulp capping agent in vital pulp therapy.

Bioactive Endodontic Hydrogels: From Parameters to Personalized Medicine

Regenerative endodontic procedures (REPs) aim at recreating dental pulp tissue using biomaterials such as hydrogels. Their bioactivity is mostly related to the nature of biomolecules or chemical compounds that compose the endodontic hydrogel. However, many other parameters, such as hydrogel concentration, bioactive molecules solubility, and apex size, were reported to influence the reciprocal host-biomaterial relationship and hydrogel behavior. The lack of knowledge regarding these various parameters, which should be considered, leads to the inability to predict the clinical outcome and suggests that the biological activity of endodontic hydrogel is impossible to anticipate and could hinder the bench-to-bedside transition. We describe, in this review, that most of these parameters could be identified, described, and studied. A second part of the review lists some challenges and perspectives, including development of future mathematical models that are able to explain, and eventually predict, the bioactivity of endodontic hydrogel used in a clinical setting.