Present and future of tissue engineering scaffolds for dentin-pulp complex regeneration

Influence of extracellular matrix scaffolds on histological outcomes of regenerative endodontics in experimental animal models: a systematic review

BACKGROUND

Decellularized extracellular matrix (dECM) from several tissue sources has been proposed as a promising alternative to conventional scaffolds used in regenerative endodontic procedures (REPs). This systematic review aimed to evaluate the histological outcomes of studies utilizing dECM-derived scaffolds for REPs and to analyse the contributing factors that might influence the nature of regenerated tissues.

METHODS

The PRISMA 2020 guidelines were used. A search of articles published until April 2024 was conducted in Google Scholar, Scopus, PubMed and Web of Science databases. Additional records were manually searched in major endodontic journals. Original articles including histological results of dECM in REPs and in-vivo studies were included while reviews, in-vitro studies and clinical trials were excluded. The quality assessment of the included studies was analysed using the ARRIVE guidelines. Risk of Bias assessment was done using the (SYRCLE) risk of bias tool.

RESULTS

Out of the 387 studies obtained, 17 studies were included for analysis. In most studies, when used as scaffolds with or without exogenous cells, dECM showed the potential to enhance angiogenesis, dentinogenesis and to regenerate pulp-like and dentin-like tissues. However, the included studies showed heterogeneity of decellularization methods, animal models, scaffold source, form and delivery, as well as high risk of bias and average quality of evidence.

DISCUSSION

Decellularized ECM-derived scaffolds could offer a potential off-the-shelf scaffold for dentin-pulp regeneration in REPs. However, due to the methodological heterogeneity and the average quality of the studies included in this review, the overall effectiveness of decellularized ECM-derived scaffolds is still unclear. More standardized preclinical research is needed as well as well-constructed clinical trials to prove the efficacy of these scaffolds for clinical translation.

OTHER

The protocol was registered in PROSPERO database #CRD42023433026. This review was funded by the Science, Technology and Innovation Funding Authority (STDF) under grant number (44426).

Tissue Regeneration on Rise: Dental Hard Tissue Regeneration and Challenges-A Narrative Review

Background

As people live longer, there is an increasing need for hard tissue regeneration and whole-tooth regeneration. Despite the advancements in the field of medicine, the field of regenerative dentistry is still challenging due to the complexity of dental hard tissues. Cross-disciplinary collaboration among material scientists, cellular biologists, and odontologists aimed at developing strategies and uncovering solutions related to dental tissue regeneration. Methodology. A search of the literature was done for pertinent research. Consistent with the Preferred Reporting Items for Systematic Review and Meta-Analysis (PRISMA) 2020 Statement, the electronic databases looked at were PubMed, Science Direct, Scopus, and Google Scholar, with the keyword search "hard dental tissue regeneration."

Results

Database analysis yielded a total of 476 articles. 222 duplicate articles have been removed in total. Articles that have no connection to the directed regeneration of hard dental tissue were disregarded. The review concluded with the inclusion of four studies that were relevant to our research objective.

Conclusion

Current molecular signaling network investigations and novel viewpoints on cellular heterogeneity have made advancements in understanding of the kinetics of dental hard tissue regeneration possible. Here, we outline the fundamentals of stem hard dental tissue maintenance, regeneration, and repair, as well as recent advancements in the field of hard tissue regeneration. These intriguing findings help establish a framework that will eventually enable basic research findings to be utilized towards oral health-improving medicines.

Functionalization of PCL-Based Fiber Scaffolds with Different Sources of Calcium and Phosphate and Odontogenic Potential on Human Dental Pulp Cells

This study investigated the incorporation of sources of calcium, phosphate, or both into electrospun scaffolds and evaluated their bioactivity on human dental pulp cells (HDPCs). Additionally, scaffolds incorporated with calcium hydroxide (CH) were characterized for degradation, calcium release, and odontogenic differentiation by HDPCs. Polycaprolactone (PCL) was electrospun with or without 0.5% w/v of calcium hydroxide (PCL + CH), nano-hydroxyapatite (PCL + nHA), or β-glycerophosphate (PCL + βGP). SEM/EDS analysis confirmed fibrillar morphology and particle incorporation. HDPCs were cultured on the scaffolds to assess cell viability, adhesion, spreading, and mineralized matrix formation. PCL + CH was also evaluated for gene expression of odontogenic markers (RT-qPCR). Data were submitted to ANOVA and Student's t-test (α = 5%). Added CH increased fiber diameter and interfibrillar spacing, whereas βGP decreased both. PCL + CH and PCL + nHA improved HDPC viability, adhesion, and proliferation. Mineralization was increased eightfold with PCL + CH. Scaffolds containing CH gradually degraded over six months, with calcium release within the first 140 days. CH incorporation upregulated DSPP and DMP1 expression after 7 and 14 days. In conclusion, CH- and nHA-laden PCL fiber scaffolds were cytocompatible and promoted HDPC adhesion, proliferation, and mineralized matrix deposition. PCL + CH scaffolds exhibit a slow degradation profile, providing sustained calcium release and stimulating HDPCs to upregulate odontogenesis marker genes.

Photothermal hydrogels for infection control and tissue regeneration

In this review, we report investigating photothermal hydrogels, innovative biomedical materials designed for infection control and tissue regeneration. These hydrogels exhibit responsiveness to near-infrared (NIR) stimulation, altering their structure and properties, which is pivotal for medical applications. Photothermal hydrogels have emerged as a significant advancement in medical materials, harnessing photothermal agents (PTAs) to respond to NIR light. This responsiveness is crucial for controlling infections and promoting tissue healing. We discuss three construction methods for preparing photothermal hydrogels, emphasizing their design and synthesis, which incorporate PTAs to achieve the desired photothermal effects. The application of these hydrogels demonstrates enhanced infection control and tissue regeneration, supported by their unique photothermal properties. Although research progress in photothermal hydrogels is promising, challenges remain. We address these issues and explore future directions to enhance their therapeutic potential.

Demineralized dentin matrix for bone regeneration in dentistry: A critical update

Over the last few decades, several new materials and techniques have been developed for bone regeneration. Scaffolds based on demineralized dentin matrix (DDM) present an attractive option due to their availability and several animal and human studies have been conducted to ascertain their utility in regenerative dentistry. The aim of this review was to summarize the recent studies conducted on DDM and used for bone grafts. PubMed, Web of Science, and Scopus were used to search for studies published within the last 10 years. The keywords and terms used were: "demineralized dentine matrix", "bone grafting", "bone augmentation" and "guided tissue regeneration" in various combinations. Original studies (in vitro, animal and human) and systematic reviews were included in the literature search. The literature search initially identified 23 studies (16 animal studies and 7 clinical reports. Most studies included in this review indicate that DDM has demonstrated promising results in a variety of dental and regenerative medicine applications. Further studies are required to completely comprehend its characteristics and prospective applications. Future studies should also focus on optimizing the processing protocols for the production of DDM-based scaffolds.

Amnion-derived hydrogels as a versatile platform for regenerative therapy: from lab to market

In recent years, the amnion (AM) has emerged as a versatile tool for stimulating tissue regeneration and has been of immense interest for clinical applications. AM is an abundant and cost-effective tissue source that does not face strict ethical issues for biomedical applications. The outstanding biological attributes of AM, including side-dependent angiogenesis, low immunogenicity, anti-inflammatory, anti-fibrotic, and antibacterial properties facilitate its usage for tissue engineering and regenerative medicine. However, the clinical usage of thin AM sheets is accompanied by some limitations, such as handling without folding or tearing and the necessity for sutures to keep the material over the wound, which requires additional considerations. Therefore, processing the decellularized AM (dAM) tissue into a temperature-sensitive hydrogel has expanded its processability and applicability as an injectable hydrogel for minimally invasive therapies and a source of bioink for the fabrication of biomimetic tissue constructs by recapitulating desired biochemical cues or pre-defined architectural design. This article reviews the multi-functionality of dAM hydrogels for various biomedical applications, including skin repair, heart treatment, cartilage regeneration, endometrium regeneration, vascular graft, dental pulp regeneration, and cell culture/carrier platform. Not only recent and cutting-edge research is reviewed but also available commercial products are introduced and their main features and shortcomings are elaborated. Besides the great potential of AM-derived hydrogels for regenerative therapy, intensive interdisciplinary studies are still required to modify their mechanical and biological properties in order to broaden their therapeutic benefits and biomedical applications. Employing additive manufacturing techniques (e.g., bioprinting), nanotechnology approaches (e.g., inclusion of various bioactive nanoparticles), and biochemical alterations (e.g., modification of dAM matrix with photo-sensitive molecules) are of particular interest. This review article aims to discuss the current function of dAM hydrogels for the repair of target tissues and identifies innovative methods for broadening their potential applications for nanomedicine and healthcare.

Histological evaluation of the regenerative potential of a novel photocrosslinkable gelatin-treated dentin matrix hydrogel in direct pulp capping: an animal study

BACKGROUND

To assess histologically the success of the pulp capping approach performed in traumatically exposed dogs' teeth using a novel injectable gelatin-treated dentin matrix light cured hydrogel (LCG-TDM) compared with LCG, MTA and TheraCal LC.

METHODS

Sixty-four dogs' teeth were divided into two groups (each including 32 teeth) based on the post-treatment evaluation period: group I: 2 weeks and group II: 8 weeks. Each group was further subdivided according to the pulp capping material into four subgroups (n = 8), with subgroup A (light-cured gelatin hydrogel) as the control subgroup, subgroup B (LCG-TDM), subgroup C (TheraCal LC), and subgroup D (MTA). Pulps were mechanically exposed in the middle of the cavity floor and capped with different materials. An assessment of periapical response was performed preoperatively and at 8 weeks. After 2 and 8-week intervals, the dogs were sacrificed, and the teeth were stained with hematoxylin-eosin and graded by using a histologic scoring system. Statistical analysis was performed using the chi-square and Kruskal-Wallis tests (p = 0.05).

RESULTS

All subgroups showed mild inflammation with normal pulp tissue at 2 weeks with no significant differences between subgroups (p ≤ 0.05), except for the TheraCal LC subgroup, which exhibited moderate inflammation (62.5%). Absence of a complete calcified bridge was reported in all subgroups at 2 weeks, while at 8 weeks, the majority of samples in the LCG-TDM and MTA-Angelus subgroups showed complete dentin bridge formation and absence of inflammatory pulp response with no significant differences between them (p ≤ 0.05). However, the formed dentin in the LCG-TDM group was significantly thicker, with layers of ordered odontoblasts identified to create a homogeneous tubular structure and numerous dentinal tubule lines suggesting a favourable trend towards dentin regeneration. TheraCal LC samples revealed a reasonably thick dentin bridge with moderate inflammation (50%) and LCG showed heavily fibrous tissue infiltrates with areas of degenerated pulp with no signs of hard tissue formation.

CONCLUSIONS

LCG-TDM, as an extracellular matrix-based material, has the potential to regenerate dentin and preserve pulp vitality, making it a viable natural alternative to silicate-based cements for healing in vivo dentin defects in direct pulp-capping procedures.

Unlocking the Potential of Cellular Guidance in Endodontics: Advancing the Process of Pulp Regeneration and Beyond

Regenerative endodontics represents a paradigm shift in dental therapy, with the potential to not only restore damaged dental tissues but also to preserve the vitality of teeth. At the heart of this innovative approach is cell homing, a technique that harnesses the body's own healing mechanisms by recruiting endogenous stem cells to the site of dental injury for effective tissue regeneration. This review delves into the intricate processes of cell homing in the context of regenerative endodontics, particularly focusing on its application in immature teeth with open apices. It examines the role of bioactive molecules, scaffolds, and growth factors in orchestrating cell migration and differentiation within the root canal space. In addition, the review addresses the current limitations in clinical practice, such as the challenges in completely regenerating the pulp-dentin complex and the unpredictability in long-term outcomes. It also explores future possibilities, including the potential for more refined and effective regenerative strategies. By providing a comprehensive overview of the current state of cell homing in regenerative endodontics, this article aims to contribute to the ongoing development of advanced therapeutic techniques that could revolutionize endodontic treatment and improve patient care.

Methylenetetrahydrofolate reductase polymorphisms in dental caries-induced pulp inflammation and regeneration of dentine-pulp complex: Future perspectives

Dental caries (DC)-induced pulp infections usually undergo the common endodontic treatment, root canal therapy (RCT). Endodontically treated teeth are devitalized, become brittle and susceptible for re-infection which eventually results in dental loss. These complications arise because the devitalized pulp losses its ability for innate homeostasis, repair and regeneration. Therefore, restoring the vitality, structure and function of the inflamed pulp and compromised dentin have become the focal points in regenerative endodontics. There are very few evidences, so far, that connect methylenetetrahydrofolate reductase single nucleotide polymorphisms (MTHFR-SNPs) and dental disorders. However, the primary consequences of MTHFR-SNPs, in terms of excessive homocysteine and folate deficiency, are well-known contributors to dental diseases. This article identifies the possible mechanisms by which MTHFR-SNP-carriers are susceptible for DC-induced pulp inflammation (PI); and discusses a cell-homing based strategy for in vivo transplantation in an orthotopic model to regenerate the functional dentine-pulp complex which includes dentinogenesis, neurogenesis and vasculogenesis, in the SNP-carriers.

Marginal adaptation, physicochemical and rheological properties of treated dentin matrix hydrogel as a novel injectable pulp capping material for dentin regeneration

BACKGROUND

Treated dentin matrix hydrogel (TDMH) has been introduced as a novel injectable direct pulp capping material. In this regard, this study aimed to evaluate its marginal adaptation, physicochemical and rheological properties for the development of clinically feasible TDMH.

METHODS

TDMH was applied to the pulp floor of prepared Class I cavities (n = 5), marginal adaptation was assessed by SEM at 1000 X magnification to detect gap between dentin and filling material. Five syringes were filled with TDMH and placed between the compression plates of a universal testing machine to evaluate injectability and gelation time was also evaluated by test vial inverting method. The microstructures of lyophilized TDMH were observed by SEM. Moreover, TDMH discs (n = 5) were prepared and the water uptake (%) was determined based on the equilibrium swelling theory state of hydrogels. Its solubility was measured after one week by the ISO standard method. Rheological behaviours of TDMH (n = 5) were analysed with a rotational rheometer by computing their complex shear modulus G* and their associated storage modulus (G') and loss modulus (G''). Statistical analysis was performed using F test (ANOVA) with repeated measures and Post Hoc Test (p = 0.05).

RESULTS

TDMH presented an overall 92.20 ± 2.95% of continuous margins. It exhibited gelation during the first minute, and injectability mean was 66 ± 0.36%. TDMH showed a highly porous structure, and the pores were interconnected with an average diameter about 5.09 ± 3.17 μm. Swelling equilibrium gradually reached at 6 days up to 377%. The prepared hydrogels and maintained their shape after absorbing over three times their original weight of water. TDMH fulfilled the requirements of ISO 6876, demonstrating a weight loss of 1.98 ± 0.09% and linear viscoelastic behaviour with G` 479.2 ± 12.7 and G`` 230.8 ± 13.8.

CONCLUSIONS

TDMH provided good marginal adaptation, appropriate physicochemical and viscoelastic properties support its use as a novel direct pulp capping material in future clinical applications.

Biomimetic Apatite/Natural Polymer Composite Granules as Multifunctional Dental Tissue Regenerative Material

This study presents a comprehensive evaluation of novel composite biomaterials designed for dental applications, aiming to potentially address the prevalent challenge of dental and periodontal tissue loss. The composites consisted of biomimetic hydroxyapatite (mHA) enriched with Mg2+, CO32-, and Zn2+ ions, type I collagen, alginate, and, additionally, chitosan and sericin. The granules were loaded with ibuprofen sodium salt. The investigation encompassed a morphology characterization, a porosity analysis, a chemical structure assessment, and an examination of the swelling behavior, drug release kinetics (ibuprofen), and release profiles of zinc and magnesium ions. The granules exhibited irregular surfaces with an enhanced homogeneity in the chitosan-coated granules and well-developed mesoporous structures. The FT-IR spectra confirmed the presence of ibuprofen sodium, despite overlapping bands for the polymers. The granules demonstrated a high water-absorption capacity, with delayed swelling observed in the chitosan-coated granules. Ibuprofen displayed burst-release profiles, especially in the G1 and G3 samples. In the case of the chitosan-coated granules (G2 and G4), lower amounts of ibuprofen were released. In turn, there was a significant difference in the released amount of magnesium and zinc ions from the granules, which was most likely caused by their different location in the hydroxyapatite crystals. The cytotoxicity assays confirmed the non-cytotoxic behavior of the biomaterial. These findings suggest the potential applicability of these biomaterials in dental scenarios, emphasizing their multifunctional and biocompatible nature.

Spatiotemporal cellular dynamics and molecular regulation of tooth root ontogeny

Tooth root development involves intricate spatiotemporal cellular dynamics and molecular regulation. The initiation of Hertwig's epithelial root sheath (HERS) induces odontoblast differentiation and the subsequent radicular dentin deposition. Precisely controlled signaling pathways modulate the behaviors of HERS and the fates of dental mesenchymal stem cells (DMSCs). Disruptions in these pathways lead to defects in root development, such as shortened roots and furcation abnormalities. Advances in dental stem cells, biomaterials, and bioprinting show immense promise for bioengineered tooth root regeneration. However, replicating the developmental intricacies of odontogenesis has not been resolved in clinical treatment and remains a major challenge in this field. Ongoing research focusing on the mechanisms of root development, advanced biomaterials, and manufacturing techniques will enable next-generation biological root regeneration that restores the physiological structure and function of the tooth root. This review summarizes recent discoveries in the underlying mechanisms governing root ontogeny and discusses some recent key findings in developing of new biologically based dental therapies.

Crucial Factors Influencing the Involvement of Odontogenic Exosomes in Dental Pulp Regeneration

Recent progress in exosome based studies has revealed that they possess several advantages over cells, including "cell-free" properties, low immunogenicity and ethical controversy, high biological safety and effective action. These characteristics confer exosomes significant advantages that allow them to overcome the limitations associated with traditional "cell therapy" by circumventing the issues of immune rejection, scarcity of donor cells, heterogeneity, and ethical concerns. Identification of a complete and effective radical treatment for irreversible pulpal disease, a common clinical problem, continues to pose challenges. Although traditional root canal therapy remains the primary clinical treatment, it does not fully restore the physiological functions of pulp. Although stem cell transplantation appears to be a relatively viable treatment strategy for pulp disease, issues such as cell heterogeneity and poor regeneration effects remain problematic. Dental pulp regeneration strategies based on "cell-free" exosome therapies explored by numerous studies appear to have shown significant advantages. In particular, exosomes derived from odontogenic stem cells have demonstrated considerable potential in tooth tissue regeneration engineering, and continue to exhibit superior therapeutic effects compared to non-odontogenic stem cell-derived exosomes. However, only a few studies have comprehensively summarised their research results, particularly regarding the critical factors involved in the process. Therefore, in this study, our purpose was to review the effects exerted by odontogenic exosomes on pulp regeneration and to analyse and discus crucial factors related to this process, thereby providing scholars with a feasible and manageable new concept with respect to regeneration schemes.

Macro, Micro, and Nano-Inspired Bioactive Polymeric Biomaterials in Therapeutic, and Regenerative Orofacial Applications

Introducing dental polymers has accelerated biotechnological research, advancing tissue engineering, biomaterials development, and drug delivery. Polymers have been utilized effectively in dentistry to build dentures and orthodontic equipment and are key components in the composition of numerous restorative materials. Furthermore, dental polymers have the potential to be employed for medication administration and tissue regeneration. To analyze the influence of polymer-based investigations on practical medical trials, it is required to evaluate the research undertaken in this sector. The present review aims to gather evidence on polymer applications in dental, oral, and maxillofacial reconstruction.

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.

Efficacy of Chitosan Scaffolded Calcium Silicate-based Cements for Treating Internal Resorption Defects with Perforation: In Vitro Study

AIM

The present study aimed to evaluate the efficacy of chitosan scaffold combined with calcium silicate cements in the management of internal resorption with perforation.

MATERIALS AND METHODS

Internal resorption cavities were simulated in 20 human permanent maxillary incisors that were then divided into two groups: group I - biodentine and group II - chitosan scaffold combined with biodentine. The samples were evaluated for the mineralization activity at the end of the 7th day and 14th day using scanning electron microscopy-energy dispersive X-ray (SEM-EDX) analysis. The data were recorded, tabulated, and then statistically analyzed.

RESULTS

From the SEM-EDX analysis, the mean score of calcium and phosphorus ion uptake by the material was obtained. Statistical analysis by nonparametric Mann-Whitney test showed that there was statistically significant difference in calcium ion uptake at the end of the 7th day (p = 0.016) and at the end of 14th day (p = 0.043) between the group biodentine and group chitosan scaffold combined with biodentine (p < 0.05).

CONCLUSION

In this present study, the use of chitosan scaffolds combined with biodentine showed a statistically significant difference in the mineralization activity when compared with pure biodentine. These scaffolded biomaterials exhibited greater potential for mineralization in vitro which can be efficiently used for the management of teeth with internal resorption with perforation. Further clinical trials are required for the understanding of their behavior in real-world scenarios.

CLINICAL SIGNIFICANCE

Calcium silicate cements have often exhibited defective hard tissue barrier formation and hence there is a pressing need to search for newer biomaterials that can overcome these shortcomings. Scaffolded biomaterials provide a controlled microcellular environment for bioactivity, and they were found to be efficient in the remineralization of tooth structure. The present study findings indicate that these chitosan scaffolds can be efficiently used in combination with calcium silicate cements for the management of internal resorption with perforation to enhance the treatment outcome.

Application of Nanomaterials in Stem Cell-Based Therapeutics for Cardiac Repair and Regeneration

Cardiovascular disease is a leading cause of disability and death worldwide. Although the survival rate of patients with heart diseases can be improved with contemporary pharmacological treatments and surgical procedures, none of these therapies provide a significant improvement in cardiac repair and regeneration. Stem cell-based therapies are a promising approach for functional recovery of damaged myocardium. However, the available stem cells are difficult to differentiate into cardiomyocytes, which result in the extremely low transplantation efficiency. Nanomaterials are widely used to regulate the myocardial differentiation of stem cells, and play a very important role in cardiac tissue engineering. This study discusses the current status and limitations of stem cells and cell-derived exosomes/micro RNAs based cardiac therapy, describes the cardiac repair mechanism of nanomaterials, summarizes the recent advances in nanomaterials used in cardiac repair and regeneration, and evaluates the advantages and disadvantages of the relevant nanomaterials. Besides discussing the potential clinical applications of nanomaterials in cardiac therapy, the perspectives and challenges of nanomaterials used in stem cell-based cardiac repair and regeneration are also considered. Finally, new research directions in this field are proposed, and future research trends are highlighted.

Biodegradation of an injectable treated dentin matrix hydrogel as a novel pulp capping agent for dentin regeneration

BACKGROUND

A novel injectable mixture termed treated dentin matrix hydrogel (TDMH) has been introduced for restoring dentin defect in DPC. However, no study evaluated its physiological biodegradation. Therefore, the present study aimed to assess scaffold homogeneity, mechanical properties and biodegradability in vitro and in vivo and the regenerated dentin induced by TDMH as a novel pulp capping agent in human permanent teeth.

METHODS

Three TDMH discs were weighted, and dry/wet ratios were calculated in four slices from each disc to evaluate homogeneity. Hydrogel discs were also analyzed in triplicate to measure the compressive strength using a universal testing machine. The in vitro degradation behavior of hydrogel in PBS at 37 °C for 2 months was also investigated by monitoring the percent weight change. Moreover, 20 intact fully erupted premolars were included for assessment of TDMH in vivo biodegradation when used as a novel injectable pulp capping agent. The capped teeth were divided into four equal groups according to extraction interval after 2-, 8-, 12- and 16-weeks, stained with hematoxylin-eosin for histological and histomorphometric evaluation. Statistical analysis was performed using F test (ANOVA) and post hoc test (p = 0.05).

RESULTS

No statistical differences among hydrogel slices were detected with (p = 0.192) according to homogeneity. TDMH compression modulus was (30.45 ± 1.11 kPa). Hydrogel retained its shape well up to 4 weeks and after 8 weeks completely degraded. Histological analysis after 16 weeks showed a significant reduction in TDMH area and a simultaneous significant increase in the new dentin area. The mean values of TDMH were 58.8% ± 5.9 and 9.8% ± 3.3 at 2 and 16 weeks, while the new dentin occupied 9.5% ± 2.8 at 2 weeks and 82.9% ± 3.8 at 16 weeks.

CONCLUSIONS

TDMH was homogenous and exhibited significant stability and almost completely recovered after excessive compression. TDMH generally maintained their bulk geometry throughout 7 weeks. The in vivo response to TDMH was characterized by extensive degradation of the hydrogel and dentin matrix particles and abundant formation of new dentin. The degradation rate of TDMH matched the rate of new dentin formation.

TRIAL REGISTRATION

PACTR201901866476410: 30/1/2019.

Chitosan/Xanthan/Hydroxyapatite-graphene oxide porous scaffold associated with mesenchymal stem cells for dentin-pulp complex regeneration

The aim of this paper was to synthesize and characterize polymeric scaffolds of Chitosan/Xanthan/Hydroxyapatite-Graphene Oxide nanocomposite associated with mesenchymal stem cells for regenerative dentistry application. The chitosan-xanthan gum (CX) complex was associated with Hydroxyapatite-Graphene Oxide (HA-GO) nanocomposite with different Graphene Oxides (GO) concentration (0.5 wt%; 1.0 wt%; 1.5 wt%). The scaffolds characterizations were performed by X-ray diffraction (XRD), Fourier Transform Infrared Spectroscopy (FTIR), Raman spectroscopy, thermogravimetric analysis (TGA), scanning electron microscopy (SEM) and contact angle. The mechanical properties were assessed by compressive strength. The in vitro bioactivity and the in vitro cytotoxicity test (MTT test) were analyzed as well. The data was submitted to the Normality and Homogeneity tests. In vitro Indirect Cytotoxicity assay data was statistically analyzed by ANOVA two-way, followed by Tukey's test (α = 0.05). Compressive strength and contact angle data were statistically analyzed by one-way ANOVA, followed by Tukey's test (α = 0.05). XRD showed the presence of Hydroxyapatite (HA) peaks in the structures CXHA, CXHAGO 0.5%,1.0% and 1.5%. FT-IR showed amino and carboxylic bands characteristic of CX. Raman spectroscopy analysis evidenced a high quality of the GO. In the TGA it was observed the mass loss associated with the CX degradation by depolymerization. SEM analysis showed pores in the scaffolds, in addition to HA incorporated and adhered to the polymer. Contact angle test showed that scaffolds have a hydrophilic characteristic, with the CX group the highest contact angle and CXHA the lowest (p < 0.05). 1.0 wt% GO significantly increased the compressive strength compared to other compositions. In the bioactivity test, the apatite crystals precipitation on the scaffold surface was observed. MTT test showed high cell viability in CXHAGO 1.0% and CXHAGO 1.5% scaffold. CXHAGO scaffolds are promising for regenerative dentistry application because they have morphological characteristics, mechanical and biological properties favorable for the regeneration process.

Applicatoin of chitosan-based hydrogel in oral tissue engineering

Pulpitis, periodontitis, jaw bone defect, and temporomandibular joint damage are common oral and maxillofacial diseases in clinic, but traditional treatments are unable to restore the structure and function of the injured tissues. Due to their good biocompatibility, biodegradability, antioxidant effect, anti-inflammatory activity, and broad-spectrum antimicrobial property, chitosan-based hydrogels have shown broad applicable prospects in the field of oral tissue engineering. Quaternization, carboxymethylation, and sulfonation are common chemical modification strategies to improve the physicochemical properties and biological functions of chitosan-based hydrogels, while the construction of hydrogel composite systems via carrying porous microspheres or nanoparticles can achieve local sequential delivery of diverse drugs or bioactive factors, laying a solid foundation for the well-organized regeneration of defective tissues. Chemical cross-linking is commonly employed to fabricate irreversible permanent chitosan gels, and physical cross-linking enables the formation of reversible gel networks. Representing suitable scaffold biomaterials, several chitosan-based hydrogels transplanted with stem cells, growth factors or exosomes have been used in an attempt to regenerate oral soft and hard tissues. Currently, remarkable advances have been made in promoting the regeneration of pulp-dentin complex, cementum-periodontium-alveolar bone complex, jaw bone, and cartilage. However, the clinical translation of chitosan-based hydrogels still encounters multiple challenges. In future, more in vivo clinical exploration under the conditions of oral complex microenvironments should be performed, and the combined application of chitosan-based hydrogels and a variety of bioactive factors, biomaterials, and state-of-the-art biotechnologies can be pursued in order to realize multifaceted complete regeneration of oral tissue.

Dentin regeneration based on tooth tissue engineering: A review

Missing or damaged teeth due to caries, genetic disorders, oral cancer, or infection may contribute to physical and mental impairment that reduces the quality of life. Despite major progress in dental tissue repair and those replacing missing teeth with prostheses, clinical treatments are not yet entirely satisfactory, as they do not regenerate tissues with natural teeth features. Therefore, much of the focus has centered on tissue engineering (TE) based on dental stem/progenitor cells to create bioengineered dental tissues. Many in vitro and in vivo studies have shown the use of cells in regenerating sections of a tooth or a whole tooth. Tooth tissue engineering (TTE), as a promising method for dental tissue regeneration, can form durable biological substitutes for soft and mineralized dental tissues. The cell-based TE approach, which directly seeds cells and bioactive components onto the biodegradable scaffolds, is currently the most potential method. Three essential components of this strategy are cells, scaffolds, and growth factors (GFs). This study investigates dentin regeneration after an injury such as caries using TE and stem/progenitor cell-based strategies. We begin by discussing about the biological structure of a dentin and dentinogenesis. The engineering of teeth requires knowledge of the processes that underlie the growth of an organ or tissue. Then, the three fundamental requirements for dentin regeneration, namely cell sources, GFs, and scaffolds are covered in the current study, which may ultimately lead to new insights in this field.

Engineering peptide-polymer hybrids for targeted repair and protection of cervical lesions

By 2060, nearly 100 million people in the U.S. will be over age 65 years. One-third of these older adults will have root caries, and nearly 80% will have dental erosion. These conditions can cause pain and loss of tooth structure that interfere with eating, speaking, sleeping, and quality of life. Current treatments for root caries and dental erosion have produced unreliable results. For example, the glass-ionomer-cement or composite-resin restorations used to treat these lesions have annual failure rates of 44% and 17%, respectively. These limitations and the pressing need to treat these conditions in the aging population are driving a focus on microinvasive strategies, such as sealants and varnishes. Sealants can inhibit caries on coronal surfaces, but they are ineffective for root caries. For healthy, functionally independent elders, chlorhexidine varnish applied every 3 months inhibits root caries, but this bitter-tasting varnish stains the teeth. Fluoride gel inhibits root caries, but requires prescriptions and daily use, which may not be feasible for some older patients. Silver diamine fluoride can both arrest and inhibit root caries but stains the treated tooth surface black. The limitations of current approaches and high prevalence of root caries and dental erosion in the aging population create an urgent need for microinvasive therapies that can: (a) remineralize damaged dentin; (b) inhibit bacterial activity; and (c) provide durable protection for the root surface. Since cavitated and non-cavitated root lesions are difficult to distinguish, optimal approaches will treat both. This review will explore the multi-factorial elements that contribute to root surface lesions and discuss a multi-pronged strategy to both repair and protect root surfaces. The strategy integrates engineered peptides, novel polymer chemistry, multi-scale structure/property characterization and predictive modeling to develop a durable, microinvasive treatment for root surface lesions.

Layered scaffolds in periodontal regeneration

Periodontitis is a common inflammatory disease in dentistry that may lead to tooth loss and aesthetic problems. Periodontal tissue has a sophisticated architecture including four sections of alveolar bone, cementum, gingiva, and periodontal ligament fiber; all these four can be damaged during periodontitis. Thus, for whole periodontal regeneration, it is important to form both hard and soft tissue structures simultaneously on the tooth root surface without forming junctional epithelium and ankylosis. This condition makes the treatment of the periodontium a challenging process. Various regenerative methods including Guided Bone/Tissue Regeneration (GBR/GTR) using various membranes have been developed. Although using such GBR/GTR membranes was successful for partial periodontal treatment, they cannot be used for the regeneration of complete periodontium. For this purpose, multilayered scaffolds are now being developed. Such scaffolds may include various biomaterials, stem cells, and growth factors in a multiphasic configuration in which each layer is designed to regenerate specific section of the periodontium. This article provides a comprehensive review of the multilayered scaffolds for periodontal regeneration based on natural or synthetic polymers, and their combinations with other biomaterials and bioactive molecules. After highlighting the challenges related to multilayered scaffolds preparation, features of suitable scaffolds for periodontal regeneration are discussed.

Application of Nano-Inspired Scaffolds-Based Biopolymer Hydrogel for Bone and Periodontal Tissue Regeneration

This review’s objectives are to provide an overview of the various kinds of biopolymer hydrogels that are currently used for bone tissue and periodontal tissue regeneration, to list the advantages and disadvantages of using them, to assess how well they might be used for nanoscale fabrication and biofunctionalization, and to describe their production processes and processes for functionalization with active biomolecules. They are applied in conjunction with other materials (such as microparticles (MPs) and nanoparticles (NPs)) and other novel techniques to replicate physiological bone generation more faithfully. Enhancing the biocompatibility of hydrogels created from blends of natural and synthetic biopolymers can result in the creation of the best scaffold match to the extracellular matrix (ECM) for bone and periodontal tissue regeneration. Additionally, adding various nanoparticles can increase the scaffold hydrogel stability and provide a number of biological effects. In this review, the research study of polysaccharide hydrogel as a scaffold will be critical in creating valuable materials for effective bone tissue regeneration, with a future impact predicted in repairing bone defects.

Tissue Engineering with Stem Cell from Human Exfoliated Deciduous Teeth (SHED) and Collagen Matrix, Regulated by Growth Factor in Regenerating the Dental Pulp

Maintaining dental pulp vitality and preventing tooth loss are two challenges in endodontic treatment. A tooth lacking a viable pulp loses its defense mechanism and regenerative ability, making it more vulnerable to severe damage and eventually necessitating extraction. The tissue engineering approach has drawn attention as an alternative therapy as it can regenerate dentin-pulp complex structures and functions. Stem cells or progenitor cells, extracellular matrix, and signaling molecules are triad components of this approach. Stem cells from human exfoliated deciduous teeth (SHED) are a promising, noninvasive source of stem cells for tissue regeneration. Not only can SHEDs regenerate dentin-pulp tissues (comprised of fibroblasts, odontoblasts, endothelial cells, and nerve cells), but SHEDs also possess immunomodulatory and immunosuppressive properties. The collagen matrix is a material of choice to provide structural and microenvironmental support for SHED-to-dentin pulp tissue differentiation. Growth factors regulate cell proliferation, migration, and differentiation into specific phenotypes via signal-transduction pathways. This review provides current concepts and applications of the tissue engineering approach, especially SHEDs, in endodontic treatment.

Anti-Inflammatory and Mineralization Effects of an ASP/PLGA-ASP/ACP/PLLA-PLGA Composite Membrane as a Dental Pulp Capping Agent

Dental pulp is essential for the development and long-term preservation of teeth. Dental trauma and caries often lead to pulp inflammation. Vital pulp therapy using dental pulp-capping materials is an approach to preserving the vitality of injured dental pulp. Most pulp-capping materials used in clinics have good biocompatibility to promote mineralization, but their anti-inflammatory effect is weak. Therefore, the failure rate will increase when dental pulp inflammation is severe. The present study developed an amorphous calcium phosphate/poly (L-lactic acid)-poly (lactic-co-glycolic acid) membrane compounded with aspirin (hereafter known as ASP/PLGA-ASP/ACP/PLLA-PLGA). The composite membrane, used as a pulp-capping material, effectively achieved the rapid release of high concentrations of the anti-inflammatory drug aspirin during the early stages as well as the long-term release of low concentrations of aspirin and calcium/phosphorus ions during the later stages, which could repair inflamed dental pulp and promote mineralization. Meanwhile, the composite membrane promoted the proliferation of inflamed dental pulp stem cells, downregulated the expression of inflammatory markers, upregulated the expression of mineralization-related markers, and induced the formation of stronger reparative dentin in the rat pulpitis model. These findings indicate that this material may be suitable for use as a pulp-capping material in clinical applications.

Progress of Research on the Application of Triple Antibiotic Paste and Hydrogel Scaffold Materials in Endodontic Revascularization: A Systematic Review

Objective

To evaluate the application of hydrogel scaffold materials and triple antibiotic paste in endodontic regeneration through literature review.

Methods

An electronic search of the literature published on PubMed, Wangfang database, and CNKI database using the search terms “endodontic regeneration,” “pulp blood flow reconstruction,” “recanalization,” “triple antibiotic paste,” and “scaffold material” was conducted. The searched literature was used for analysis. Results and Conclusion. Hydrogels regulate stem cell fates, modulate growth factor release, and encapsulate antibacterial and anti-inflammatory drugs. The triple antibiotic paste is composed of metronidazole, ciprofloxacin, and minocycline, which exhibits promising antibacterial effects and duration at appropriate concentrations, with low cytotoxicity, and effectively promotes the preservation and regeneration of pulp tissues and the formation of dental hard tissues. However, issues such as tooth discoloration and bacterial drug resistance also exist. The present article reviews the progress of research on the application of hydrogel scaffold materials and triple antibiotic paste in endodontic revascularization.

Influencing factors of pulp-dentin complex regeneration and related biological strategies

Regenerative endodontic therapy (RET) utilizing tissue engineering approach can promote the regeneration of pulp-dentin complex to restore pulp vascularization, neuralization, immune function and tubular dentin, therefore the regenerated pulp-dentin complex will have normal function. Multiple factors may significantly affect the efficacy of RET, including stem cells, biosignaling molecules and biomaterial scaffolds. Stem cells derived from dental tissues (such as dental pulp stem cells) exhibit certain advantages in RET. Combined application of multiple signaling molecules and activation of signal transduction pathways such as Wnt/β-catenin and BMP/Smad play pivotal roles in enhancing the potential of stem cell migration, proliferation, odontoblastic differentiation, and nerve and blood vessel regeneration. Biomaterials suitable for RET include naturally-derived materials and artificially synthetic materials. Artificially synthetic materials should imitate natural tissues for biomimetic modification in order to realize the temporal and spatial regulation of pulp-dentin complex regeneration. The realization of pulp-dentin complex regeneration depends on two strategies: stem cell transplantation and stem cell homing. Stem cell homing strategy does not require the isolation and culture of stem cells in vitro, so is better for clinical application. However, in order to achieve the true regeneration of pulp-dentin complex, problems related to improving the success rate of stem cell homing and promoting their proliferation and differentiation need to be solved. This article reviews the influencing factors of pulp-dentin complex regeneration and related biological strategies, and discusses the future research direction of RET, to provide reference for clinical translation and application of RET.

Advances on Hydrogels for Oral Science Research

Hydrogels are biocompatible polymer systems, which have become a hotspot in biomedical research. As hydrogels mimic the structure of natural extracellular matrices, they are considered as good scaffold materials in the tissue engineering area for repairing dental pulp and periodontal damages. Combined with different kinds of stem cells and growth factors, various hydrogel complexes have played an optimistic role in endodontic and periodontal tissue engineering studies. Further, hydrogels exhibit biological effects in response to external stimuli, which results in hydrogels having a promising application in local drug delivery. This review summarized the advances of hydrogels in oral science research, in the hopes of providing a reference for future applications.

MTA-Enriched Polymeric Scaffolds Enhanced the Expression of Angiogenic Markers in Human Dental Pulp Stem Cells

Revascularization of the pulp tissue is one of the fundamental processes and challenges in regenerative endodontic procedures (REPs). In this regard, the current study is aimed at synthesizing the mineral trioxide aggregate- (MTA-) based scaffolds as a biomaterial for REPs. Poly (ε-caprolactone) (PCL)/chitosan (CS)/MTA scaffolds were constructed and evaluated by FTIR, SEM, XRD, and TGA analyses. Proliferation and adhesion of human dental pulp stem cells (hDPSCs) were assessed on these scaffolds by scanning electron microscopy (SEM) and MTT assays, respectively. The expression of angiogenic markers was investigated in gene and protein levels by real-time PCR and western blotting tests. Our results indicated that the obtained appropriate physicochemical characteristics of scaffolds could be suitable for REPs. The adhesion and proliferation level of hDPSCs were significantly increased after seeding on PCL/CS/MTA scaffolds. The expression levels of VEGFR-2, Tie2, and Angiopoietin-1 genes were statistically increased on the PCL/CS/MTA scaffold. In support of these findings, western blotting results showed the upregulation of these markers at protein levels in PCL/CS/MTA scaffold ( $P<0.05$ ). The current study results suggested that PCL/CS/MTA scaffolds provide appropriate structures for the adhesion and proliferation of hDPSCs besides induction of the angiogenesis process in these cells.

The Application of Pulp Tissue Derived-Exosomes in Pulp Regeneration: A Novel Cell-Homing Approach

Purpose

Exosomes derived from stem cells, as an alternative to stem cells themselves, have been employed for dental pulp regeneration. However, it is not known whether exosomes can recruit host cells to the regeneration process. In this study, we built a “cell homing” model to determine whether exosomes derived from dental pulp tissue (DPT-exos) can regenerate dental pulp by recruiting the stem cells from the apical dental papilla (SCAPs).

Methods

Exosomes were isolated from the dental pulp tissue (DPT-exos) and dental pulp stem cells (DPC-exos) of swine. The effects of the exosomes on SCAPs were compared using CKK-8, Transwell, angiogenesis, and odontogenic induction assays. DPT-exos and DPC-exos were investigated in an in vivo “cell homing” model using swine teeth to compare their roles in pulp regeneration. To build the model, we placed SCAP-containing collagen gel at the root tip and filled the cavity of the treated dental matrix (TDM) with DPT-exos and DPC-exos-laden scaffolds, which would be expected to recruit SCAPs to the pulp cavity. The complex was then implanted subcutaneously into immunodeficient nude mice. After eight weeks, tissue samples were taken and analyzed histologically to determine whether the DPT-exos contributed to pulp regeneration through “cell homing”.

Results

Exosomes were successfully extracted from dental pulp tissue and confirmed to be exosomes. In vitro tests confirmed that DPT-exos performed better than DPC-exos in promoting the migration, proliferation, and differentiation of SCAPs. Furthermore, DPT-exos recruited SCAPs to regenerate dental pulp-like connective tissue in vivo containing collagen, odontoblasts, and enriched predentin-like tissue. Blood vessel growth was demonstrated by immunofluorescence.

Conclusion

This study demonstrated the ability of DPT-exos to induce SCAPs to regenerate connective tissue similar to natural dental pulp. This technique has the potential for treating pulp deficiency caused by various pulp diseases.

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.

Green Hydrogels Composed of Sodium Mannuronate/Guluronate, Gelatin and Biointeractive Calcium Silicates/Dicalcium Phosphate Dihydrate Designed for Oral Bone Defects Regeneration

Innovative green, eco-friendly, and biologically derived hydrogels for non-load bearing bone sites were conceived and produced. Natural polysaccharides (copolymers of sodium D-mannuronate and L-guluronate) with natural polypeptides (gelatin) and bioactive mineral fillers (calcium silicates CaSi and dicalcium phosphate dihydrate DCPD) were used to obtain eco-sustainable biomaterials for oral bone defects. Three PP-x:y formulations were prepared (PP-16:16, PP-33:22, and PP-31:31), where PP represents the polysaccharide/polypeptide matrix and x and y represent the weight % of CaSi and DCPD, respectively. Hydrogels were tested for their chemical-physical properties (calcium release and alkalizing activity in deionized water, porosity, solubility, water sorption, radiopacity), surface microchemistry and micromorphology, apatite nucleation in HBSS by ESEM-EDX, FT-Raman, and micro-Raman spectroscopies. The expression of vascular (CD31) and osteogenic (alkaline phosphatase ALP and osteocalcin OCN) markers by mesenchymal stem cells (MSCs) derived from human vascular walls, cultured in direct contact with hydrogels or with 10% of extracts was analysed. All mineral-filled hydrogels, in particular PP-31:31 and PP-33:22, released Calcium ions and alkalized the soaking water for three days. Calcium ion leakage was high at all the endpoints (3 h-28 d), while pH values were high at 3 h-3 d and then significantly decreased after seven days (p < 0.05). Porosity, solubility, and water sorption were higher for PP-31:31 (p < 0.05). The ESEM of fresh samples showed a compact structure with a few pores containing small mineral granules agglomerated in some areas (size 5-20 microns). PP-CTRL degraded after 1-2 weeks in HBSS. EDX spectroscopy revealed constitutional compounds and elements of the hydrogel (C, O, N, and S) and of the mineral powders (Ca, Si and P). After 28 days in HBSS, the mineral-filled hydrogels revealed a more porous structure, partially covered with a thicker mineral layer on PP-31:31. EDX analyses of the mineral coating showed Ca and P, and Raman revealed the presence of B-type carbonated apatite and calcite. MSCs cultured in contact with mineral-filled hydrogels revealed the expression of genes related to vascular (CD31) and osteogenic (mainly OCN) differentiation. Lower gene expression was found when cells were cultured with extracts added to the culture medium. The incorporation of biointeractive mineral powders in a green bio-derived algae-based matrix allowed to produce bioactive porous hydrogels able to release biologically relevant ions and create a suitable micro-environment for stem cells, resulting in interesting materials for bone regeneration and healing in oral bone defects.

Functionalized self-assembled peptide RAD/Dentonin hydrogel scaffold promotes dental pulp regeneration

RADA16-I is an ion-complementary self-assembled peptide with a regular folded secondary conformation and can be assembled into an ordered nanostructure. Dentonin is an extracellular matrix phosphate glycoprotein functional peptide motif-containing RGD and SGDG motifs. In this experiment, we propose to combine RAD and Dentonin to form a functionalized self-assembled peptide RAD/Dentonin hydrogel scaffold. Furthermore, we expect that the RAD with the addition of functional motif Dentonin can promote pulp regeneration. The study analyzed the physicochemical properties of RAD/Dentonin through circular dichroism, morphology scanning, and rheology. Besides, we examined the scaffold's biocompatibility by immunofluorescent staining, CCK-8 method, Live/Dead fluorescent staining, and 3D reconstruction. Finally, we applied ALP activity assay, RT-qPCR, and Alizarin red S staining to detect the effect of RAD/Dentonin on the odontogenic differentiation of human dental pulp stem cells (hDPSCs). The results showed that RAD/Dentonin spontaneously assembles into a hydrogel with aβ-sheet-based nanofiber network structure.In vitro, RAD/Dentonin has superior biocompatibility and enhances adhesive proliferation, migration, odontogenic differentiation, and mineralization deposition of hDPSCs. In conclusion, the novel self-assembled peptide RAD/Dentonin is a new scaffold material suitable for cell culture and has promising applications as a scaffold for endodontic tissue engineering.

Effect of Magnesium on Dentinogenesis of Human Dental Pulp Cells

Introducing therapeutic ions into pulp capping materials has been considered a new approach for enhancing regeneration of dental tissues. However, no studies have been reported on its dentinogenic effects on human dental pulp cells (HDPCs). This study was designed to investigate the effects of magnesium (Mg²⁺) on cell attachment efficiency, proliferation, differentiation, and mineralization of HDPCs. HDPCs were cultured with 0.5 mM, 1 mM, 2 mM, 4 mM, and 8 mM concentrations of supplemental Mg²⁺ and 0 mM (control). Cell attachment was measured at 4, 8, 12, 16, and 20 hours. Cell proliferation rate was evaluated at 3, 7, 10, 14, and 21 days. Crystal violet staining was used to determine cell attachment and proliferation rate. Alkaline phosphatase (ALP) activity was assessed using the fluorometric assay at 7, 10, and 14 days. Mineralization of cultures was measured by Alizarin red staining. Statistical analysis was done using multiway analysis of variance (multiway ANOVA) with Wilks' lambda test. Higher cell attachment was shown with 0.5 mM and 1 mM at 16 hours compared to control (P < 0.0001). Cells with 0.5 mM and 1 mM supplemental Mg²⁺ showed significantly higher proliferation rates than control at 7, 10, 14, and 21 days (P < 0.0001). However, cell proliferation rates decreased significantly with 4 mM and 8 mM supplemental Mg²⁺ at 14 and 21 days (P < 0.0001). Significantly higher levels of ALP activity and mineralization were observed in 0.5 mM, 1 mM, and 2 mM supplemental Mg²⁺ at 10 and 14 days (P < 0.0001). However, 8 mM supplemental Mg²⁺ showed lower ALP activity compared to control at 14 days (P < 0.0001), while 4 mM and 8 mM supplemental Mg²⁺showed less mineralization compared to control (P < 0.0001). The study indicated that the optimal (0.5–2 mM) supplemental Mg²⁺ concentrations significantly upregulated HDPCs by enhancing cell attachment, proliferation rate, ALP activity, and mineralization. Magnesium-containing biomaterials could be considered for a future novel dental pulp-capping additive in regenerative endodontics.

Regeneration of dentin-pulp complex by using dental pulp stem cells in dog

INTRODUCTION

Although missing tooth is not life-threatening, it affects the quality of daily life. Stem cells have emerged as an important player in the generation and maintenance of many tissues. The role of scaffolds has changed from a passive carrier to a bioactive matrix, which can be used to induce cellular behavior. The aim of this study was to determine the possibility of regeneration of dentin-pulp complex with dental pulp stem cells (DPSCs) in an animal model.

MATERIALS AND METHODS

In this animal study after extraction of DPSCs and cultivation, 10 types of scaffolds were made by using platelet-rich plasma (PRP), cancellous bone, and collagen pad. They were inserted in different parts of the dog's mouth. After the 4^th month, the area was operated, and the scaffolds were removed.

RESULTS

Microscopic examination revealed no sign of cell differentiation and formation of new structures in those models which used collagen scaffolds. However, the dentin-pulp complex emerged in models that the combination of bone scaffolds and PRP or stem cells was used.

CONCLUSION

Using bone scaffolds in combination with PRP or DPSCs to regenerate dentin-pulp complex in dog helped odontoblastic and pulpal differentiation as well as the formation of predentin and tubular dentin.

Natural Polymers for the Maintenance of Oral Health: Review of Recent Advances and Perspectives

The success of modern dental treatment is strongly dependent on the materials used both temporarily and permanently. Among all dental materials, polymers are a very important class with a wide spectrum of applications. This review aims to provide a state-of-the-art overview of the recent advances in the field of natural polymers used to maintain or restore oral health. It focuses on the properties of the most common proteins and polysaccharides of natural origin in terms of meeting the specific biological requirements in the increasingly demanding field of modern dentistry. The use of naturally derived polymers in different dental specialties for preventive and therapeutic purposes has been discussed. The major fields of application cover caries and the management of periodontal diseases, the fabrication of membranes and scaffolds for the regeneration of dental structures, the manufacturing of oral appliances and dentures as well as providing systems for oral drug delivery. This paper also includes a comparative characteristic of natural and synthetic dental polymers. Finally, the current review highlights new perspectives, possible future advancements, as well as challenges that may be encountered by researchers in the field of dental applications of polymers of natural origin.

Lipid-Based Drug Delivery Systems in Regenerative Medicine

The most important goal of regenerative medicine is to repair, restore, and regenerate tissues and organs that have been damaged as a result of an injury, congenital defect or disease, as well as reversing the aging process of the body by utilizing its natural healing potential. Regenerative medicine utilizes products of cell therapy, as well as biomedical or tissue engineering, and is a huge field for development. In regenerative medicine, stem cells and growth factor are mainly used; thus, innovative drug delivery technologies are being studied for improved delivery. Drug delivery systems offer the protection of therapeutic proteins and peptides against proteolytic degradation where controlled delivery is achievable. Similarly, the delivery systems in combination with stem cells offer improvement of cell survival, differentiation, and engraftment. The present review summarizes the significance of biomaterials in tissue engineering and the importance of colloidal drug delivery systems in providing cells with a local environment that enables them to proliferate and differentiate efficiently, resulting in successful tissue regeneration.

Functional Dental Pulp Regeneration: Basic Research and Clinical Translation

Pulpal and periapical diseases account for a large proportion of dental visits, the current treatments for which are root canal therapy (RCT) and pulp revascularisation. Despite the clinical signs of full recovery and histological reconstruction, true regeneration of pulp tissues is still far from being achieved. The goal of regenerative endodontics is to promote normal pulp function recovery in inflamed or necrotic teeth that would result in true regeneration of the pulpodentinal complex. Recently, rapid progress has been made related to tissue engineering-mediated pulp regeneration, which combines stem cells, biomaterials, and growth factors. Since the successful isolation and characterisation of dental pulp stem cells (DPSCs) and other applicable dental mesenchymal stem cells, basic research and preclinical exploration of stem cell-mediated functional pulp regeneration via cell transplantation and cell homing have received considerably more attention. Some of this effort has translated into clinical therapeutic applications, bringing a ground-breaking revolution and a new perspective to the endodontic field. In this article, we retrospectively examined the current treatment status and clinical goals of pulpal and periapical diseases and scrutinized biological studies of functional pulp regeneration with a focus on DPSCs, biomaterials, and growth factors. Then, we reviewed preclinical experiments based on various animal models and research strategies. Finally, we summarised the current challenges encountered in preclinical or clinical regenerative applications and suggested promising solutions to address these challenges to guide tissue engineering-mediated clinical translation in the future.

The Role of Biomaterials and Biocompatible Materials in Implant-Supported Dental Prosthesis

The dental implant is one of the appropriate instances of the different dental materials and their application, which is the combined procedure of technology and science in physics, biomechanics, and surface chemistry from macroscale to nanoscale surface engineering and manufactured technologies. In recent decades, biomaterials in implant therapy promote bone response and biomechanical ability, which is long-term from surgical equipment to final prosthetic restoration. Biomaterials have a crucial role in rehabilitating the damaged structure of the tooth and supplying acceptable outcomes correlated with clinical performance. There are some challenges in implantation such as bleeding, mobility, peri-implant infections, and the solution associated with modern strategies which are regarded to biomaterials. Various materials have been known as promising candidates for coatings of dental implants which contain polyhydroxyalkanoates, calcium phosphate, carbon, bisphosphonates, hydroxyapatite, bone stimulating factors, bioactive glass, bioactive ceramics, collagen, chitosan, metal and their alloys, fluoride, and titanium/titanium nitride. It is pivotal that biomaterials should be biodegradable; for example, polyhydroxyalkanoates are biodegradable; also, they do not have bad effects on tissues and cells. Despite this, biomaterials have important roles in prosthetic conditions such as dental pulp regeneration, the healing process, and antibacterial and anti-inflammatory effects. In this review study, the role of biocompatible materials in dental implants is investigated in in vitro and in vivo studies.

A Comprehensive Review on the Applications of Exosomes and Liposomes in Regenerative Medicine and Tissue Engineering

Tissue engineering and regenerative medicine are generally concerned with reconstructing cells, tissues, or organs to restore typical biological characteristics. Liposomes are round vesicles with a hydrophilic center and bilayers of amphiphiles which are the most influential family of nanomedicine. Liposomes have extensive research, engineering, and medicine uses, particularly in a drug delivery system, genes, and vaccines for treatments. Exosomes are extracellular vesicles (EVs) that carry various biomolecular cargos such as miRNA, mRNA, DNA, and proteins. As exosomal cargo changes with adjustments in parent cells and position, research of exosomal cargo constituents provides a rare chance for sicknesses prognosis and care. Exosomes have a more substantial degree of bioactivity and immunogenicity than liposomes as they are distinctly chiefly formed by cells, which improves their steadiness in the bloodstream, and enhances their absorption potential and medicinal effectiveness in vitro and in vivo. In this review, the crucial challenges of exosome and liposome science and their functions in disease improvement and therapeutic applications in tissue engineering and regenerative medicine strategies are prominently highlighted.

Multicellular Spheroids Formation on Hydrogel Enhances Osteogenic/Odontogenic Differentiation of Dental Pulp Stem Cells Under Magnetic Nanoparticles Induction

Introduction

Promotion odontogenic differentiation of dental pulp stem cells (DPSCs) is essential for dentin regeneration. Physical cellular microenvironment is of critical importance for stem cells differentiation and influences the function of other biological/chemical factors to differentiation.

Methods

Based on adjusting the mechanical/interfacial properties of hydrogels, multicellular spheroids (MCSs) of DPSCs generated through self-organization. The spheroids were characterized by immunofluorescent staining and flow cytometry. Quantitative real-time polymerase chain reaction, alkaline phosphatase (ALP) activity assay, ALP staining and Alizarin Red S staining were performed to evaluate the osteogenic/odontogenic differentiation of DPSCs with or without magnetic iron oxide nanoparticles (IONPs) induction.

Results

MCSs of DPSCs exhibited a significant upregulation of E-cadherin and N-cadherin and enriched CD146 positive subpopulation, along with a stronger osteogenic/odontogenic differentiation ability. Moreover, DPSCs spheroids showed more substantial osteogenic differentiation tendency than the classical two-dimensional cultured DPSCs under the stimulation of magnetic IONPs.

Conclusion

Three-dimensional spheroids culture of DPSCs based on composite viscoelastic materials combined with mechanical/magnetic stimulation may provide a theoretical basis for the subsequent development of dentin or bone regeneration technology.

Effects of different aperture-sized type I collagen/silk fibroin scaffolds on the proliferation and differentiation of human dental pulp cells

This study aimed at evaluate the effects of different aperture-sized type I collagen/silk fibroin (CSF) scaffolds on the proliferation and differentiation of human dental pulp cells (HDPCs). The CSF scaffolds were designed with 3D mapping software Solidworks. Three different aperture-sized scaffolds (CSF1-CSF3) were prepared by low-temperature deposition 3D printing technology. The morphology was observed by scanning electron microscope (SEM) and optical coherence tomography. The porosity, hydrophilicity and mechanical capacity of the scaffold were detected, respectively. HDPCs (third passage, 1 × 10⁵ cells) were seeded into each scaffold and investigated by SEM, CCK-8, alkaline phosphatase (ALP) activity and HE staining. The CSF scaffolds had porous structures with macropores and micropores. The macropore size of CSF1 to CSF3 was 421 ± 27 μm, 579 ± 36 μm and 707 ± 43 μm, respectively. The porosity was 69.8 ± 2.2%, 80.1 ± 2.8% and 86.5 ± 3.3%, respectively. All these scaffolds enhanced the adhesion and proliferation of HDPCs. The ALP activity in the CSF1 group was higher than that in the CSF3 groups (P < 0.01). HE staining showed HDPCs grew in multilayer within the scaffolds. CSF scaffolds significantly improved the adhesion and ALP activity of HDPCs. CSF scaffolds were promising candidates in dentine-pulp complex regeneration.

Preparation of Absorption-Resistant Hard Tissue Using Dental Pulp-Derived Cells and Honeycomb Tricalcium Phosphate

In recent years, there has been increasing interest in the treatment of bone defects using undifferentiated mesenchymal stem cells (MSCs) in vivo. Recently, dental pulp has been proposed as a promising source of pluripotent mesenchymal stem cells (MSCs), which can be used in various clinical applications. Dentin is the hard tissue that makes up teeth, and has the same composition and strength as bone. However, unlike bone, dentin is usually not remodeled under physiological conditions. Here, we generated odontoblast-like cells from mouse dental pulp stem cells and combined them with honeycomb tricalcium phosphate (TCP) with a 300 μm hole to create bone-like tissue under the skin of mice. The bone-like hard tissue produced in this study was different from bone tissue, i.e., was not resorbed by osteoclasts and was less easily absorbed than the bone tissue. It has been suggested that hard tissue-forming cells induced from dental pulp do not have the ability to induce osteoclast differentiation. Therefore, the newly created bone-like hard tissue has high potential for absorption-resistant hard tissue repair and regeneration procedures.

The effects and potential applications of concentrated growth factor in dentin-pulp complex regeneration

The dentin-pulp complex is essential for the long-term integrity and viability of teeth but it is susceptible to damage caused by external factors. Because traditional approaches for preserving the dentin-pulp complex have various limitations, there is a need for novel methods for dentin-pulp complex reconstruction. The development of stem cell-based tissue engineering has given rise to the possibility of combining dental stem cells with a tissue-reparative microenvironment to promote dentin-pulp complex regeneration. Concentrated growth factor, a platelet concentrate, is a promising scaffold for the treatment of dentin-pulp complex disorders. Given its characteristics of autogenesis, convenience, usability, and biodegradability, concentrated growth factor has gained popularity in medical and dental fields for repairing bone defects and promoting soft-tissue healing. Numerous in vitro studies have demonstrated that concentrated growth factor can promote the proliferation and migration of dental stem cells. Here, we review the current state of knowledge on the effects of concentrated growth factor on stem cells and its potential applications in dentin-pulp complex regeneration.

Hard Dental Tissues Regeneration-Approaches and Challenges

With the development of the modern concept of tissue engineering approach and the discovery of the potential of stem cells in dentistry, the regeneration of hard dental tissues has become a reality and a priority of modern dentistry. The present review reports the recent advances on stem-cell based regeneration strategies for hard dental tissues and analyze the feasibility of stem cells and of growth factors in scaffolds-based or scaffold-free approaches in inducing the regeneration of either the whole tooth or only of its component structures.

Chemometrics-Assisted Raman Spectroscopy Characterization of Tunable Polymer-Peptide Hybrids for Dental Tissue Repair

The interfaces that biological tissues form with biomaterials are invariably defective and frequently the location where failure initiates. Characterizing the phenomena that lead to failure is confounded by several factors including heterogeneous material/tissue interfaces. To seamlessly analyze across these diverse structures presents a wealth of analytical challenges. This study aims to develop a molecular-level understanding of a peptide-functionalized adhesive/collagen hybrid biomaterial using Raman spectroscopy combined with chemometrics approach. An engineered hydroxyapatite-binding peptide (HABP) was copolymerized in dentin adhesive and dentin was demineralized to provide collagen matrices that were partially infiltrated with the peptide-functionalized adhesive. Partial infiltration led to pockets of exposed collagen-a condition that simulates defects in adhesive/dentin interfaces. The spectroscopic results indicate that co-polymerizable HABP tethered to the adhesive promoted remineralization of the defects. The spatial distribution of collagen, adhesive, and mineral as well as crystallinity of the mineral across this heterogeneous material/tissue interface was determined using micro-Raman spectroscopy combined with chemometrics approach. The success of this combined approach in the characterization of material/tissue interfaces stems from its ability to extract quality parameters that are related to the essential and relevant portions of the spectral data, after filtering out noise and non-relevant information. This ability is critical when it is not possible to separate components for analysis such as investigations focused on, in situ chemical characterization of interfaces. Extracting essential information from complex bio/material interfaces using data driven approaches will improve our understanding of heterogeneous material/tissue interfaces. This understanding will allow us to identify key parameters within the interfacial micro-environment that should be harnessed to develop durable biomaterials.

Microenvironment Influences Odontogenic Mesenchymal Stem Cells Mediated Dental Pulp Regeneration

Dental pulp as a source of nutrition for the whole tooth is vulnerable to trauma and bacterial invasion, which causes irreversible pulpitis and pulp necrosis. Dental pulp regeneration is a valuable method of restoring the viability of the dental pulp and even the whole tooth. Odontogenic mesenchymal stem cells (MSCs) residing in the dental pulp environment have been widely used in dental pulp regeneration because of their immense potential to regenerate pulp-like tissue. Furthermore, the regenerative abilities of odontogenic MSCs are easily affected by the microenvironment in which they reside. The natural environment of the dental pulp has been proven to be capable of regulating odontogenic MSC homeostasis, proliferation, and differentiation. Therefore, various approaches have been applied to mimic the natural dental pulp environment to optimize the efficacy of pulp regeneration. In addition, odontogenic MSC aggregates/spheroids similar to the natural dental pulp environment have been shown to regenerate well-organized dental pulp both in preclinical and clinical trials. In this review, we summarize recent progress in odontogenic MSC-mediated pulp regeneration and focus on the effect of the microenvironment surrounding odontogenic MSCs in the achievement of dental pulp regeneration.

Magnesium Ammonium Phosphate Composite Cell-Laden Hydrogel Promotes Osteogenesis and Angiogenesis In Vitro

Injectable hydrogels provide an effective strategy for minimally invasive treatment on irregular bony defects in the maxillofacial region. To improve the osteoinduction of gelatin methacrylate (GelMA), we fabricated a three-dimensional (3D) culture system based on the incorporation of magnesium ammonium phosphate hexahydrate (struvite) into GelMA. The optimal concentration of struvite was investigated using the struvite extracts, and 500 μg mL^-1 was found to be the most suitable concentration for the osteogenesis of dental pulp stem cells (DPSCs) and angiogenesis of human umbilical vein endothelial cells (HUVECs). We prepared the GelMA composite (MgP) with 500 μg mL^-1 struvite. Struvite did not affect the cross-linking of GelMA and released Mg²⁺ during degradation. The cell delivery system using MgP improved the laden-cell viability, upregulated the expression of osteogenic and angiogenic-differentiation-related genes, and promoted cell migration. Overall, the modifications made to the GelMA in this study improved osteoinduction and demonstrated great potential for application in vascularized bone tissue regeneration.