Histologic Evaluation of Regenerative Endodontic Procedures with the Use of Chitosan Scaffolds in Immature Dog Teeth with Apical Periodontitis

Histological evaluation of different concentrations of hyaluronic-acid-added zinc oxide eugenol on rat molar pulp

Hyaluronic acid (HA), known for diverse properties, was investigated for its potential in dental pulp therapy. This study investigated the potential of HA in dental pulp therapy by examining the physical properties and effects of zinc oxide eugenol (ZOE) pulpotomy materials containing varying HA concentrations on rat molar teeth. In vitro tests assessed compressive strength and hardness of ZOE materials blended with HA (0.5%, 1%, 3%) and HA gels (0.54%, 0.8%). 120 samples, encompassing the control group, underwent compressive strength testing, while 60 samples were designated for hardness assessment. In vivo experiments on rat molars studied histological effects of HA-containing ZOE on dental pulp over 1 week and 1 month. Gels with HA concentrations of 0.5%, 1%, and 0.54% were used in pulpotomy on 22 rats. Each rat underwent the procedure on four teeth, with one tooth serving as a control, totaling 88 teeth subjected to the intervention. In the analyses, SPSS 22.0 was used and the significance level was set at P = 0.05. Findings showed that HA at 0.5% maintained compressive strength, but higher concentrations decreased mechanical properties significantly (P = 0.001). Histological assessments indicated better outcomes with lower HA concentrations in terms of odontoblast layer continuity (P = 0.005 at 1 month) and pulp vitality (P = 0.001 at 1 week and P = 0.018 at 1 month). The study suggests HA holds promise for pulpotomy and regenerative endodontic treatments, but further research is needed to understand long-term clinical implications.

Effect of simultaneous and sequential use of TGF-β1 and TGF-β3 with FGF-2 on teno/ligamentogenic differentiation of periodontal ligament stem cells

OBJECTIVE

The periodontal ligament is a crucial part of the periodontium, and its regeneration is challenging. This study compares the effect of simultaneous and sequential use of FGF-2 and TGF-β1 with FGF-2 and TGF-β3 on the periodontal ligament stem cells (PDLSCs) teno/ligamentogenic differentiation.

DESIGN

This study comprises ten different groups. A control group with only PDLSCs; FGF-2 group containing PDLSCs with a medium culture supplemented with FGF-2 (50 ng/mL). In other experimental groups, different concentrations (5 ng/mL or 10 ng/mL) of TGF-β1&-β3 simultaneously or sequentially were combined with FGF-2 on the cultured PDLSCs. TGF-β was added to the medium after day 3 in the sequential groups. Methyl Thiazolyl Tetrazolium (MTT) assay on days 3, 5, and 7 and Quantitative Real-time Polymerase Chain Reaction (RT-qPCR) analysis after day 7 were conducted to investigate PLAP1, SCX, and COL3A1, RUNX2 genes. All experiments were conducted in a triplicate. The One-way and Two-way ANOVA with Tukey post hoc were utilized to analyze the results of the MTT and RT-qPCR tests, respectively. A p-value less than 0.05 is considered significant.

RESULTS

The proliferation of cells on days 3, 5, and 7 was not significantly different among different experimental groups (P > 0.05). A higher expression of the PLAP1, SCX, and COL3A1 have been seen in groups with sequential use of growth factors; among these groups, the group using 5 ng/mL of TGF-β3 led other groups with the most amount of significant upregulation in PLAP1(17.69 ± 1.11 fold; P < 0.0001), SCX (5.71 ± 0.38 fold; P < 0.0001), and COL1A3 (6.35 ± 0.39 fold; P < 0.0001) expression, compared to the control group. The expression of the RUNX2 decreased in all groups compared to the control group; this reduction was more in groups with sequential use of growth factors.

CONCLUSION

The sequential use of growth factors can be more effective than simultaneous use in teno/ligamentogenic differentiation of PDLSCs. Moreover, treatment with 5 ng/mL TGF-β3 after FGF-2 was more effective than TGF-β1.

A Literature Review of the Effect of Heat on the Physical-Chemical Properties of Calcium Silicate-Based Sealers

INTRODUCTION

Recently, calcium silicate-based sealers (CSSs) have gained popularity in endodontic practice due to their biocompatibility and antimicrobial properties. They are considered viable alternatives to epoxy resin-based sealers. With the increased use of CSSs and warm vertical compaction techniques in root canal treatment, evaluating the impact of heat on CSSs properties is essential, therefore this review aimed to present a qualitative synthesis of available in vitro studies assessing the impact of heat on the physical-chemical properties of CSSs.

METHODS

Following the Preferred Reporting Items for Systematic Reviews and Meta-Analysis 2020 guidelines, a systematic advanced electronic search was performed in Scopus, Embase, Medline (via PubMed), Web of Science, and Cochrane databases in November 2023 and updated in April 2024. In vitro studies that evaluated the physical-chemical properties of CSSs were eligible. PRILE 2021 guidelines were used for the assessment of the risk of bias-included studies.

RESULTS

The search identified a total of 6421 preliminary results and 10 studies were included for qualitative assessment. Eleven different physiochemical properties were assessed by the included studies. Setting time and flow were the most evaluated property among the studies. A qualitative synthesis of the evidence on each property is presented.

CONCLUSIONS

Based on the in vitro studies assessed in the present systematic review, results reveal that exposing CSSs to heat can accelerate their setting time, reduce their flow, and increase their film thickness. Concerns persist regarding solubility, viscosity, radiopacity, dimensional change, microhardness, porosity, and compressive strength, requiring further research. Certain CSSs, such as MTA Fillapex and Endosequence BC sealer HiFlow, show minimal changes under heat, making them potential candidates for warm filling techniques.

Final irrigation with bioglass solution in regenerative endodontic procedure induces tissue formation inside the root canals, collagen maturation, proliferation cell and presence of osteocalcin

AIM

To evaluate the influence of an experimental solution of cobalt-doped F18 bioactive glass (F18Co) on tissue repair following regenerative endodontic procedure (REP) in rat molars.

METHODOLOGY

The F18Co solution was prepared at a ratio of 1:5 F18Co powder to distilled water. The right or left upper first molars of 12 Wistar rats were used, where the pulps were exposed, removed, and irrigated with 2.5% sodium hypochlorite (NaOCl), followed by 17% ethylenediaminetetraacetic acid (EDTA) (5 min each). Subsequently, the molars were divided into two groups (n = 6): REP-SS and REP-F18Co, where they received a final irrigation (5 min) with saline solution (SS) or F18Co solution, respectively. Then, intracanal bleeding was induced, and the tooth was sealed. Untreated molars were used as controls (n = 3). At 21 days, the rats were euthanized, and the specimens were processed for analysis of mineralized tissue and soft tissue formation inside the root canal using haematoxylin-eosin. The presence and maturation of collagen were evaluated by Masson's trichrome and picrosirius red staining. Immunolabelling analyses of proliferating cell nuclear antigen (PCNA) and osteocalcin (OCN) were performed. The data were submitted to the Mann-Whitney U-test (p < .05).

RESULTS

There was a similar formation of mineralized tissue in thickness and length in REP-SS and REP-F18Co groups (p > .05). Regarding the presence of newly formed soft tissue, most specimens of the REP-F18Co had tissue formation up to the cervical third of the canal, whilst the REP-SS specimens showed formation up to the middle third (p < .05), and there was higher maturation of collagen in REP-F18Co (p < .05). The number of PCNA-positive cells found in the apical third of the root canal was significantly higher in the F18Co group, as well as the OCN immunolabelling, which was severe in most specimens of REP-F18Co, and low in most specimens of REP-SS.

CONCLUSION

The final irrigation with F18Co bioactive glass solution in REP did not influence mineralized tissue formation but induced soft tissue formation inside the root canals, with higher collagen maturation, and an increase in PCNA-positive cells and OCN immunolabelling.

GelMA-based hydrogel biomaterial scaffold: A versatile platform for regenerative endodontics

Endodontic therapy, while generally successful, is primarily limited to mature teeth, hence the pressing need to explore regenerative approaches. Gelatin methacryloyl (GelMA) hydrogels have emerged as pivotal biomaterials, promising a bright future for dental pulp regeneration. Despite advancements in tissue engineering and biomaterials, achieving true pulp tissue regeneration remains a formidable task. GelMA stands out for its injectability, rapid gelation, and excellent biocompatibility, serving as the cornerstone of scaffold materials. In the pursuit of dental pulp regeneration, GelMA holds significant potential, facilitating the delivery of stem cells, growth factors, and other vital substances crucial for tissue repair. Presently, in the field of dental pulp regeneration, researchers have been diligently utilizing GelMA hydrogels as engineering scaffolds to transport various effective substances to promote pulp regeneration. However, existing research is relatively scattered and lacks comprehensive reviews and summaries. Therefore, the primary objective of this article is to elucidate the application of GelMA hydrogels as regenerative scaffolds in this field, thereby providing clear direction for future researchers. Additionally, this article provides a comprehensive discussion on the synthesis, characterization, and application of GelMA hydrogels in root canal therapy regeneration. Furthermore, it offers new application strategies and profound insights into future challenges, such as optimizing GelMA formulations to mimic the complex microenvironment of pulp tissue and enhancing its integration with host tissues.

Physical training attenuates systemic cytokine response and tissue damage triggered by apical periodontitis

Apical periodontitis (AP) is a condition characterized by inflammatory and infectious components in the tooth canal. AP affects periradicular tissues and has systemic repercussions. Physical exercise is a structured activity that requires cardiorespiratory function, and can modulate the inflammatory profile in pathological conditions. As a result, this study aimed to determine the effects of aerobic physical training (PT) on the alveolar bone with and without AP, and its systemic inflammatory repercussions. AP was induced in the mandibular first molars, and PT was performed on a treadmill for five consecutive days over four weeks, with progressive increases in speed and activity time. Blood samples were collected to determine serum cytokine levels using immunoassays, and alveolar bone samples were collected for histopathological evaluation, lesion volume and microarchitecture assessment using computed microtomography. Animals with AP had increased pro-inflammatory cytokines levels compared to those without AP; however, these levels were attenuated or restored by PT. Compared to the AP group, the AP + PT group had a smaller lesion volume and greater preservation of the bone trabeculae in the remaining alveolar bone surrounding the lesion. In overall, PT minimized the severity of AP proving to be a valid strategy for individuals undergoing endodontic treatment.

The osteoinductive potential of different root-filling materials in a rat femur model

In pediatric dentistry, the enduring success of root-end filling materials employed for the establishment of apical plugs in immature teeth undergoing endodontic intervention is contingent upon their possessing a robust osteoinductive capacity. Hence, the primary objective of this study was to histologically assess the osteoinductive potential of four distinct dental materials, specifically recommended for retrograde filling applications, utilizing an animal hard tissue model. Within the designed experimental model, two bone defects measuring 2 mm in diameter and 2 mm in depth were created in both femurs of a cohort comprising 21 male Wistar albino rats. The first defect in the right femur was left blank as the control group, and Neo MTA Plus was placed in the second defect. The EndoSequence BCRRM Fast Set Putty was placed in the first of the defects on the left femur, and Endo Repair was placed in the second defect. Subjects were sacrificed after 7, 14, and 28 days of follow-up, and sections were examined to assess the degree of inflammation, connective tissue formation, and new bone formation. The data were statistically evaluated with Kruskal‒Wallis and post hoc Dunn's tests using SPSS 12 software. The bone healing levels of the Neo MTA Plus group were significantly higher than those of the other groups in all periods (p < 0.05). Bone organization in all groups decreased over time, and fibrous tissue was enriched. The results of this study demonstrate that NeoMta Plus has superior osteoinductive properties compared to other materials but that EndoSequence and Endo Repair have the potential to be developed.

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.

Interactions of Neuronally Induced Stem Cells from Apical Papilla Spheres, Stems Cells from Apical Papilla, and Human Umbilical Vascular Endothelial Cells on Vasculogenesis and Neurogenesis

INTRODUCTION

Stem cell-based dental pulp regeneration has been extensively studied, mainly focusing on exploiting dental stem cells' osteogenic and angiogenic potentials. Dental stem cells' neurogenic role is often overlooked. Stem cells from apical papilla (SCAPs), originating from the neural crest and capable of sphere formation, display potent neurogenic capacity. This study aimed to investigate the interactions of neuronally induced stem cells from apical papilla (iSCAP) spheres, SCAPs, and human umbilical vascular endothelial cells (HUVECs) on vasculogenesis and neurogenesis.

METHODS

SCAPs were isolated and characterized using flow cytometry and multilineage differentiation assays. SCAP monolayer culture and spheres were neuronally induced by a small molecule neural induction medium, and the neural gene expression and neurite formation at days 0, 3, and 7 were evaluated by reverse transcription-quantitative polymerase chain reaction (RT-qPCR) and using phase-contrast light and fluorescence microscopy. Direct coculture or pulp-on-chip was used to investigate iSCAP sphere interaction with SCAPs and HUVECs. RT-qPCR, fluorescence microscopy, and immunostaining with β-tubulin III, alpha-smooth muscle actin, and CD31 were used to study neural gene expression, neurite formation, and neurovascular cell interactions.

RESULTS

Neural induction medium with small molecules rapidly induced SCAP differentiation toward neural-like cells. Gene expression of Nestin, β-tubulin III, microtubule-associated protein 2, neuron-specific enolase, and NeuN was higher in iSCAP spheres than in iSCAPs. iSCAP spheres formed more and longer neurites compared with iSCAPs. iSCAP sphere, HUVEC, and SCAP direct coculture significantly enhanced vessel formation along with up-regulated VEGF (P < .001) and multiple neural markers, such as Nestin (P < .01), microtubule-associated protein 2 (P < .001), S100 (P < .001), and NG2 (P < .001). iSCAP spheres, SCAPs, and HUVECs cultured in a pulp-on-chip system promoted endothelial and neural cell migration toward each other and alpha-smooth muscle actin-positive and CD31-positive cells assembling for the vascular constitution.

CONCLUSIONS

iSCAP-formed spheres interact with SCAPs and HUVECs, promoting vasculogenesis and neurogenesis.

In vivo cytotoxicity analysis of bioceramic root canal sealers on zebrafish embryo

Background

This study evaluated the cytotoxicity of four bioceramic root canal sealers (RCSs) in vivo. The embryonic zebrafish characteristics, such as mortality, survival, hatching, and general morphology, served as the parameters for assessing cytotoxicity.

Methods

The RCSs, namely GuttaFlow Bioseal, MTA Fillapex, CeraSeal Bioceramic, and iRoot SP, were mixed according to the manufacturer's guidelines. The extract solution was prepared by immersing the set RCS into 1X dilution of E3 solution. Then, the extract solution was delivered into a Petri dish where zebrafish embryos were allowed to develop. Cytotoxicity was evaluated 24, 48, 72, and 96 hours after fertilization.

Results

The Kruskal-Wallis test showed that except for GuttaFlow Bioseal, the mortality, survival, and hatching of zebrafish embryos for the remaining three bioceramic RCSs were significantly different from the negative controls (P<0.05). Significant differences were also evident in the mortality, survival, and hatching of zebrafish embryos between GuttaFlow Bioseal and three other RCSs (P<0.05).

Conclusion

GuttaFlow Bioseal was less cytotoxic than other bioceramics RCSs; MTA Fillapex, CeraSeal Bioceramic root canal sealer, and iRoot SP root canal sealer exhibited comparable cytotoxicity.

Scaffolds for Dentin-Pulp Complex Regeneration

Background and Objectives: Regenerative dentistry aims to regenerate the pulp-dentin complex and restore those of its functions that have become compromised by pulp injury and/or inflammation. Scaffold-based techniques are a regeneration strategy that replicate a biological environment by utilizing a suitable scaffold, which is considered crucial for the successful regeneration of dental pulp. The aim of the present review is to address the main characteristics of the different scaffolds, as well as their application in dentin-pulp complex regeneration. Materials and Methods: A narrative review was conducted by two independent reviewers to answer the research question: What type of scaffolds can be used in dentin-pulp complex regeneration? An electronic search of PubMed, EMBASE and Cochrane library databases was undertaken. Keywords including "pulp-dentin regeneration scaffold" and "pulp-dentin complex regeneration" were used. To locate additional reports, reference mining of the identified papers was undertaken. Results: A wide variety of biomaterials is already available for tissue engineering and can be broadly categorized into two groups: (i) natural, and (ii) synthetic, scaffolds. Natural scaffolds often contain bioactive molecules, growth factors, and signaling cues that can positively influence cell behavior. These signaling molecules can promote specific cellular responses, such as cell proliferation and differentiation, crucial for effective tissue regeneration. Synthetic scaffolds offer flexibility in design and can be tailored to meet specific requirements, such as size, shape, and mechanical properties. Moreover, they can be functionalized with bioactive molecules, growth factors, or signaling cues to enhance their biological properties and the manufacturing process can be standardized, ensuring consistent quality for widespread clinical use. Conclusions: There is still a lack of evidence to determine the optimal scaffold composition that meets the specific requirements and complexities needed for effectively promoting dental pulp tissue engineering and achieving successful clinical outcomes.

Pathogenesis of non-infection related inflammatory root resorption in permanent teeth: A narrative review

BACKGROUND

The mechanism of action of root resorption in a permanent tooth can be classified as infection-related (e.g., microbial infection) or non-infection-related (e.g., sterile damage). Infection induced root resorption occurs due to bacterial invasion. Non-infection-related root resorption stimulates the immune system through a different mechanism.

OBJECTIVES

The aim of this narrative review is to describe the pathophysiologic process of non-infection-related inflammatory processes involved in root resorption of permanent teeth.

METHODS

A literature search on root resorption was conducted using Scopus (PubMed and Medline) and Google Scholar databases to highlight the pathophysiology of bone and root resorption in non-infection-related situations. The search included key words covering the relevant category. It included in vitro and in vivo studies, systematic reviews, case series, reviews, and textbooks in English. Conference proceedings, lectures and letters to the editor were excluded.

RESULTS

Three types of root resorption are related to the non-infection mechanism of action, which includes surface resorption due to either trauma or excessive orthodontic forces, external replacement resorption and external cervical resorption. The triggers are usually damage associated molecular patterns and hypoxia conditions. During this phase macrophages and clastic cells act to eliminate the damaged tissue and bone, eventually enabling root resorption and bone repair as part of wound healing.

DISCUSSION

The resorption of the root occurs during the inflammatory phase of wound healing. In this phase, damaged tissues are recognized by macrophages and neutrophiles that secrete interlaukines such as TNF-α, IL-1, IL-6, IL-8. Together with the hypoxia condition that accelarates the secretion of growth factors, the repair of the damaged perioduntiom, including damaged bone, is initiated. If the precementum and cementoblast are injured, root resorption can occur.

CONCLUSIONS

Wound healing exhibits different patterns of action that involves immune stimulation in a bio-physiological activity, that occurs in the proper sequence, with overlapping phases. Two pathologic conditions, DAMPs and hypoxia, can activate the immune cells including clastic cells, eliminating damaged tissue and bone. Under certain conditions, root resorption occurs as a side effect.

Long-term follow-up of single-visit pulp revascularisation for the dens evaginatus and dens invaginatus: Cases report

This article documents cases of single-visit pulp revascularisation for dens evaginatus and dens invaginatus, without using intracranial medicaments or antibiotics, aiming to provide a potentially applicable protocol for pulp revascularisation procedure in a single-visit. Two patients with chief complaints of pain and swelling visited a dental hospital. Radiographs revealed that the causative teeth had an open apex and periapical radiolucency, and the teeth were diagnosed as pulp necrosis and acute apical abscess or symptomatic apical periodontitis. For both cases, single-visit revascularisation was completed without intracanal medicaments or antibiotics. The patients were periodically recalled to evaluate periapical healing after treatment. The apical lesion healed, and the root dentin thickening was observed. The single-visit pulp revascularisation procedure without using specific intracanal medicaments can produce clinically favourable results for these dental anomalies.

The Importance of Chitosan Coatings in Dentistry

A Chitosan is a copolymer of N-acetyl-D-glucose amine and D-glucose amine that can be easily produced. It is a polymer that is widely utilized to create nanoparticles (NPs) with specific properties for applications in a wide range of human activities. Chitosan is a substance with excellent prospects due to its antibacterial, anti-inflammatory, antifungal, haemostatic, analgesic, mucoadhesive, and osseointegrative qualities, as well as its superior film-forming capacity. Chitosan nanoparticles (NPs) serve a variety of functions in the pharmaceutical and medical fields, including dentistry. According to recent research, chitosan and its derivatives can be embedded in materials for dental adhesives, barrier membranes, bone replacement, tissue regeneration, and antibacterial agents to improve the management of oral diseases. This narrative review aims to discuss the development of chitosan-containing materials for dental and implant engineering applications, as well as the challenges and future potential. For this purpose, the PubMed database (Medline) was utilised to search for publications published less than 10 years ago. The keywords used were "chitosan coating" and "dentistry". After carefully selecting according to these keywords, 23 articles were studied. The review concluded that chitosan is a biocompatible and bioactive material with many benefits in surgery, restorative dentistry, endodontics, prosthetics, orthodontics, and disinfection. Furthermore, despite the fact that it is a highly significant and promising coating, there is still a demand for various types of coatings. Chitosan is a semi-synthetic polysaccharide that has many medical applications because of its antimicrobial properties. This article aims to review the role of chitosan in dental implantology.

Chitin scaffolds derived from the marine demosponge Aplysina fistularis stimulate the differentiation of dental pulp stem cells

The use of stem cells for tissue regeneration is a prominent trend in regenerative medicine and tissue engineering. In particular, dental pulp stem cells (DPSCs) have garnered considerable attention. When exposed to specific conditions, DPSCs have the ability to differentiate into osteoblasts and odontoblasts. Scaffolds are critical for cell differentiation because they replicate the 3D microenvironment of the niche and enhance cell adhesion, migration, and differentiation. The purpose of this study is to present the biological responses of human DPSCs to a purified 3D chitin scaffold derived from the marine demosponge Aplysina fistularis and modified with hydroxyapatite (HAp). Responses examined included proliferation, adhesion, and differentiation. The control culture consisted of the human osteoblast cell line, hFOB 1.19. Electron microscopy was used to examine the ultrastructure of the cells (transmission electron microscopy) and the surface of the scaffold (scanning electron microscopy). Cell adhesion to the scaffolds was determined by neutral red and crystal violet staining methods. An alkaline phosphatase (ALP) assay was used for assessing osteoblast/odontoblast differentiation. We evaluated the expression of osteogenic marker genes by performing ddPCR for ALP, RUNX2, and SPP1 mRNA expression levels. The results show that the chitin biomaterial provides a favorable environment for DPSC and hFOB 1.19 cell adhesion and supports both cell proliferation and differentiation. The chitin scaffold, especially with HAp modification, isolated from A. fistularis can make a significant contribution to tissue engineering and regenerative medicine.

New Insights in Hydrogels for Periodontal Regeneration

Periodontitis is a destructive inflammatory disease characterized by microbial infection that damages the tissues supporting the tooth (alveolar bone, gingiva, periodontal ligament, and cementum), ultimately resulting in the loss of teeth. The ultimate goal of periodontal therapy is to achieve the regeneration of all of the periodontal tissues. Thus, tissue engineering approaches have been evolving from simple membranes or grafts to more complex constructs. Hydrogels are highly hydrophilic polymeric networks with the ability to simulate the natural microenvironment of cells. In particular, hydrogels offer several advantages when compared to other forms of scaffolds, such as tissue mimicry and sustained drug delivery. Moreover, hydrogels can maintain a moist environment similar to the oral cavity. Hydrogels allow for precise placement and retention of regenerative materials at the defect site, minimizing the potential for off-target effects and ensuring that the treatment is focused on the specific defect site. As a mechanism of action, the sustained release of drugs presented by hydrogels allows for control of the disease by reducing the inflammation and attracting host cells to the defect site. Several therapeutic agents, such as antibiotics, anti-inflammatory and osteogenic drugs, have been loaded into hydrogels, presenting effective benefits in periodontal health and allowing for sustained drug release. This review discusses the causes and consequences of periodontal disease, as well as the advantages and limitations of current treatments applied in clinics. The main components of hydrogels for periodontal regeneration are discussed focusing on their different characteristics, outcomes, and strategies for drug delivery. Novel methods for the fabrication of hydrogels are highlighted, and clinical studies regarding the periodontal applications of hydrogels are reviewed. Finally, limitations in current research are discussed, and potential future directions are proposed.

Complex Evaluation of Nanocomposite-Based Hydroxyapatite for Biomedical Applications

A magnesium-doped hydroxyapatite in chitosan matrix (MgHApC) sample was developed as a potential platform for numerous applications in the pharmaceutical, medical, and food industries. Magnesium-doped hydroxyapatite suspensions in the chitosan matrix were obtained by the coprecipitation technique. The surface shape and morphological features were determined by scanning electron microscopy (SEM). The hydrodynamic diameter of the suspended particles was determined by Dynamic light scattering (DLS) measurements. The stability of MgHApC suspensions was evaluated by ultrasonic measurements. The hydrodynamic diameter of the MgHApC particles in suspension was 29.5 nm. The diameter of MgHApC particles calculated from SEM was 12.5 ± 2 nm. Following the SEM observations, it was seen that the MgHApC particles have a spherical shape. The Fourier-transform infrared spectroscopy (FTIR) studies conducted on MgHApC proved the presence of chitosan and hydroxyapatite in the studied specimens. In vitro antimicrobial assays were performed on Escherichia coli ATCC 25922, Staphylococcus aureus ATCC 25923, Pseudomonas aeruginosa ATCC 27853, and Candida albicans ATCC 10231 microbial strains. The antimicrobial experiments showed that MgHApC exhibited very good antimicrobial properties against all the tested microorganisms. More than that, the results of the in vitro studies revealed that the antimicrobial properties of the samples depend on the incubation time. The evaluation of the sample's cytotoxicity was performed using the human colon cancer (HCT-8) cell line. Our results suggested the great potential of MgHApC to be used in future applications in the field of biomedical applications (e.g., dentistry, orthopedics, etc.).

Modulation of blood redox status by the progression of induced apical periodontitis in rats

This study aimed to investigate if apical periodontitis in different periods changes systemic levels of the antioxidant and pro-oxidant parameters in Wistar rats. Twenty-four rats were randomly allocated into healthy animals, apical periodontitis at 14 days (AP14) and apical periodontitis at 28 days (AP28). The first mandibular molars were accessed in the AP groups, and the pulp chamber was exposed to the oral environment, inducing the apical lesion. After 14 and 28 days, the animals were anesthetized, euthanized, and hemimandibles were collected for micro-computed tomography (micro-CT) analysis to measure lesion volume, bone volume (BV), percent of bone to total tissue volume (BV/TV), trabecular thickness (Tb.Th), trabecular number (Tb.N), and trabecular space (Tb.Sp). A histological examination of the remaining bone was also performed. Finally, blood samples were collected for oxidative biochemistry analysis, investigating glutathione (GSH), Trolox equivalent antioxidant capacity (TEAC), and lipid peroxidation (TBARS). The lesion volume was greater at 28 than at 14 days, as shown by micro-CT. AP14 and AP28 had decreased BV and Tb.Th, but only AP28 showed a reduction in BV/TV. Tb.N and Tb. Sp were increased in apical periodontitis at 28 days. In the histopathological analysis, AP14 had focal regions of moderate mononuclear inflammatory infiltrate, and AP28 had an intense inflammatory infiltrate with bacterial colonies. In the biochemical evaluation, GSH, TEAC, and TBARS were increased after 14 days. However, GSH returned to control levels, TEAC was similar to AP14, and TBARS increased significantly after 28 days. Therefore, the oxidative biochemistry response was modulated according to the progression of periapical damage. After 14 days, the organism could still react to the injury. However, at 28 days, the antioxidant response decreased, associated with an increase in TBARS.

Stem Cells from the Apical Papilla (SCAPs): Past, Present, Prospects, and Challenges

Dental diseases occurring on young permanent teeth usually lead to the premature arrest of tooth root development. Sustained tooth root elongation is necessary to achieve the goal of long-term preservation of affected teeth. To this end, stem cell-based regenerative endodontic treatment has been regarded as one of the most promising strategies for treating young permanent teeth with pulp and periapical infections. Endogenous stem cells residing in the apical papilla, named stem cells from the apical papilla (SCAPs), have been intensively investigated due to their critical roles in pulp regeneration and root redevelopment. The present review summarizes advances in the field of SCAPs studies and discusses the challenges that need to be further addressed.

Micro-CT Evaluation of Spontaneous Apexification of an Immature Tooth following Trauma

This case reports on the micro-computerised tomography (CT) images of a periapical calcified dome following spontaneous apexification as a subsequence of trauma. An immature, maxillary central incisor was found to be non-vital one month following trauma. The tooth had minimal signs of structural damage; however, there was radiographic evidence of spontaneous apexification. The tooth suffered a second traumatic episode two years later and was decoronated to facilitate bone retention during osseous development. The patient presented with swelling and pain 36 months later, and the tooth root was extracted. The root was embedded in resin, and cross-sectional images were obtained using micro-CT. Analysis of the images provided insight into the structure of the calcified dome that formed following the first traumatic injury.

Synthesis, Characterization, Properties, and Biomedical Application of Chitosan-Based Hydrogels

The prospective applications of chitosan-based hydrogels (CBHs), a category of biocompatible and biodegradable materials, in biomedical disciplines such as tissue engineering, wound healing, drug delivery, and biosensing have garnered great interest. The synthesis and characterization processes used to create CBHs play a significant role in determining their characteristics and effectiveness. The qualities of CBHs might be greatly influenced by tailoring the manufacturing method to get certain traits, including porosity, swelling, mechanical strength, and bioactivity. Additionally, characterization methods aid in gaining access to the microstructures and properties of CBHs. Herein, this review provides a comprehensive assessment of the state-of-the-art with a focus on the affiliation between particular properties and domains in biomedicine. Moreover, this review highlights the beneficial properties and wide application of stimuli-responsive CBHs. The main obstacles and prospects for the future of CBH development for biomedical applications are also covered in this review.

Hydrogels for Oral Tissue Engineering: Challenges and Opportunities

Oral health is crucial to daily life, yet many people worldwide suffer from oral diseases. With the development of oral tissue engineering, there is a growing demand for dental biomaterials. Addressing oral diseases often requires a two-fold approach: fighting bacterial infections and promoting tissue growth. Hydrogels are promising tissue engineering biomaterials that show great potential for oral tissue regeneration and drug delivery. In this review, we present a classification of hydrogels commonly used in dental research, including natural and synthetic hydrogels. Furthermore, recent applications of these hydrogels in endodontic restorations, periodontal tissues, mandibular and oral soft tissue restorations, and related clinical studies are also discussed, including various antimicrobial and tissue growth promotion strategies used in the dental applications of hydrogels. While hydrogels have been increasingly studied in oral tissue engineering, there are still some challenges that need to be addressed for satisfactory clinical outcomes. This paper summarizes the current issues in the abovementioned application areas and discusses possible future developments.

Gelatin methacryloyl hydrogel as an injectable scaffold with multi-therapeutic effects to promote antimicrobial disinfection and angiogenesis for regenerative endodontics

Regenerative endodontics represents a paradigm shift in dental pulp therapy for necrotic young permanent teeth. However, there are still challenges associated with attaining maximum root canal disinfection while supporting angiogenesis and preserving resident stem cells viability and differentiation capacity. Here, we developed a hydrogel system by incorporating antibiotic-eluting fiber-based microparticles in gelatin methacryloyl (GelMA) hydrogel to gather antimicrobial and angiogenic properties while prompting minimum cell toxicity. Minocycline (MINO) or clindamycin (CLIN) was introduced into a polymer solution and electrospun into fibers, which were further cryomilled to attain MINO- or CLIN-eluting fibrous microparticles. To obtain hydrogels with multi-therapeutic effects, MINO- or CLIN-eluting microparticles were suspended in GelMA at distinct concentrations. The engineered hydrogels demonstrated antibiotic-dependent swelling and degradability while inhibiting bacterial growth with minimum toxicity in dental-derived stem cells. Notably, compared to MINO, CLIN hydrogels enhanced the formation of capillary-like networks of endothelial cells in vitro and the presence of widespread vascularization with functioning blood vessels in vivo. Our data shed new light onto the clinical potential of antibiotic-eluting gelatin methacryloyl hydrogel as an injectable scaffold with multi-therapeutic effects to promote antimicrobial disinfection and angiogenesis for regenerative endodontics.

Stem cell-derived exosomes for dentin-pulp complex regeneration: a mini-review

This mini-review was conducted to present an overview of the use of exosomes in regenerating the dentin-pulp complex (DPC). The PubMed and Scopus databases were searched for relevant articles published between January 1, 2013 and January 1, 2023. The findings of basic in vitro studies indicated that exosomes enhance the proliferation and migration of mesenchymal cells, as human dental pulp stem cells, via mitogen-activated protein kinases and Wingless-Int signaling pathways. In addition, they possess proangiogenic potential and contribute to neovascularization and capillary tube formation by promoting endothelial cell proliferation and migration of human umbilical vein endothelial cells. Likewise, they regulate the migration and differentiation of Schwann cells, facilitate the conversion of M1 pro-inflammatory macrophages to M2 anti-inflammatory phenotypes, and mediate immune suppression as they promote regulatory T cell conversion. Basic in vivo studies have indicated that exosomes triggered the regeneration of dentin-pulp-like tissue, and exosomes isolated under odontogenic circumstances are particularly strong inducers of tissue regeneration and stem cell differentiation. Exosomes are a promising regenerative tool for DPC in cases of small pulp exposure or for whole-pulp tissue regeneration.

Effect of Intracoronal Sealing Biomaterials on the Histological Outcome of Endodontic Revitalisation in Immature Sheep Teeth-A Pilot Study

The influence of intracoronal sealing biomaterials on the newly formed regenerative tissue after endodontic revitalisation therapy remains unexplored. The objective of this study was to compare the gene expression profiles of two different tricalcium silicate-based biomaterials alongside the histological outcomes of endodontic revitalisation therapy in immature sheep teeth. The messenger RNA expression of TGF-β, BMP2, BGLAP, VEGFA, WNT5A, MMP1, TNF-α and SMAD6 was evaluated after 1 day with qRT-PCR. For evaluation of histological outcomes, revitalisation therapy was performed using Biodentine (n = 4) or ProRoot white mineral trioxide aggregate (WMTA) (n = 4) in immature sheep according to the European Society of Endodontology position statement. After 6 months' follow-up, one tooth in the Biodentine group was lost to avulsion. Histologically, extent of inflammation, presence or absence of tissue with cellularity and vascularity inside the pulp space, area of tissue with cellularity and vascularity, length of odontoblast lining attached to the dentinal wall, number and area of blood vessels and area of empty root canal space were measured by two independent investigators. All continuous data were subjected to statistical analysis using Wilcoxon matched-pairs signed rank test at a significance level of p < 0.05. Biodentine and ProRoot WMTA upregulated the genes responsible for odontoblast differentiation, mineralisation and angiogenesis. Biodentine induced the formation of a significantly larger area of neoformed tissue with cellularity, vascularity and increased length of odontoblast lining attached to the dentinal walls compared to ProRoot WMTA (p < 0.05), but future studies with larger sample size and adequate power as estimated by the results of this pilot study would confirm the effect of intracoronal sealing biomaterials on the histological outcome of endodontic revitalisation.

May carriers at nanoscale improve the Endodontic's future?

Nanocarriers (NCs) are dynamic nanovehicles used to transport bioactive derivatives like therapeutical formulations, drugs and/or dyes. The current review assists in understanding the mechanism of action of several recent developed NCs with antimicrobial purposes. Here, nine NCs varieties are portrayed with focus on nineteen approaches that are fulfil described based on outcomes obtained from in vitro antimicrobial assays. All approaches have previously been verified and we underline the biochemical challenges of all NCs, expecting that the present data may encourage the application of NCs in endodontic antimicrobial basic research. Methodological limitations and the evident base gaps made not possible to draw a definite conclusion about the best NCs for achieving efficient antimicrobial outcomes in endodontic studies. Due to the lack of pre-clinical trials and the scarce number of clinical trials in this emergent area, there is still much room for improvement on several fronts.

Next-generation biomaterials for dental pulp tissue immunomodulation

OBJECTIVES

The current standard for treating irreversibly damaged dental pulp is root canal therapy, which involves complete removal and debridement of the pulp space and filling with an inert biomaterial. A regenerative approach to treating diseased dental pulp may allow for complete healing of the native tooth structure and enhance the long-term outcome of once-necrotic teeth. The aim of this paper is, therefore, to highlight the current state of dental pulp tissue engineering and immunomodulatory biomaterials properties, identifying exciting opportunities for their synergy in developing next-generation biomaterials-driven technologies.

METHODS

An overview of the inflammatory process focusing on immune responses of the dental pulp, followed by periapical and periodontal tissue inflammation are elaborated. Then, the most recent advances in treating infection-induced inflammatory oral diseases, focusing on biocompatible materials with immunomodulatory properties are discussed. Of note, we highlight some of the most used modifications in biomaterials' surface, or content/drug incorporation focused on immunomodulation based on an extensive literature search over the last decade.

RESULTS

We provide the readers with a critical summary of recent advances in immunomodulation related to pulpal, periapical, and periodontal diseases while bringing light to tissue engineering strategies focusing on healing and regenerating multiple tissue types.

SIGNIFICANCE

Significant advances have been made in developing biomaterials that take advantage of the host's immune system to guide a specific regenerative outcome. Biomaterials that efficiently and predictably modulate cells in the dental pulp complex hold significant clinical promise for improving standards of care compared to endodontic root canal therapy.

In vitro, ex vivo, and in vivo models for dental pulp regeneration

Based on the concept of tissue engineering (Cells-Scaffold-Bioactive molecules), regenerative endodontics appeared as a new notion for dental endodontic treatment. Its approaches aim to preserve dental pulp vitality (pulp capping) or to regenerate a vascularized pulp-like tissue inside necrotic root canals by cell homing. To improve the methods of tissue engineering for pulp regeneration, numerous studies using in vitro, ex vivo, and in vivo models have been performed. This review explores the evolution of laboratory models used in such studies and classifies them according to different criteria. It starts from the initial two-dimensional in vitro models that allowed characterization of stem cell behavior, through 3D culture matrices combined with dental tissue and finally arrives at the more challenging ex vivo and in vivo models. The travel which follows the elaboration of such models reveals the difficulty in establishing reproducible laboratory models for dental pulp regeneration. The development of well-established protocols and new laboratory ex vivo and in vivo models in the field of pulp regeneration would lead to consistent results, reduction of animal experimentation, and facilitation of the translation to clinical practice.

Calcium Silicate-Based Sealer Dentinal Tubule Penetration-A Systematic Review of In Vitro Studies

The aim of this systematic review was to perform a qualitative synthesis of in vitro studies which evaluate and compare the penetration of calcium silicate-based sealers into dentinal tubules. A systematic advanced search was performed in Scopus, Embase, Medline (via PubMed), Web of Science, and Cochrane databases on the 1 December 2022. In vitro studies that compared the tubular penetration of at least two calcium silicate-based sealers in extracted human teeth were eligible. PRILE 2021 guidelines were used for the assessment of the risk of bias included studies. The search identified a total of 680 preliminary records, among which 12 studies were eligible for review. The most used methodology to evaluate sealer penetration was the use of a fluorochrome together with the tested sealers and the analysis of their penetration under confocal laser microscopy. Regarding the results of the included studies, calcium silicate-based sealers exhibit a favorable dentinal tubule penetration. Tubular penetration, however, can be affected by factors such as the irrigation protocol, sealer activation, the filling method used, and root canal morphology. EndoSequence BC Sealer showed the highest sealer penetration among the tested sealers. The influence of different fluorochromes on the results of dentinal tubule penetration studies should also be further explored. The in vitro nature of the included studies limits the applicability of the results into the clinical setting. Prospero registration: CRD42022383896.

Regenerative Endodontics-Reviving the Pulp the Natural Way: A Case Report

Regenerative endodontic therapy (RET) offers a novel treatment option for developing teeth with pulp necrosis. In the current instance, RET was used to treat an immature mandibular permanent first molar that had been identified with irreversible pulpitis. The root canals were treated with triple antibiotic paste (TAP) and 1.5% sodium hypochlorite (NaOCl) irrigation. TAP was removed, and 17% ethylenediaminetetraacetic acid (EDTA) was used to treat the root canals during the second visit. As a scaffold, Platelet-rich fibrin (PRF) was applied. Mineral trioxide aggregate (MTA) was applied over PRF, and composite resin was used to repair the teeth. Radiographs taken from the posterior were utilized to assess the healing. The teeth displayed no signs of pain and healing after the six-month follow-up periods, and pulp sensibility tests using a cold and electric pulp tester produced no results. Conservative treatment options should be considered to save immature permanent teeth and assist in the regeneration of the root apex.

Polymeric Scaffolds Used in Dental Pulp Regeneration by Tissue Engineering Approach

Currently, the challenge in dentistry is to revitalize dental pulp by utilizing tissue engineering technology; thus, a biomaterial is needed to facilitate the process. One of the three essential elements in tissue engineering technology is a scaffold. A scaffold acts as a three-dimensional (3D) framework that provides structural and biological support and creates a good environment for cell activation, communication between cells, and inducing cell organization. Therefore, the selection of a scaffold represents a challenge in regenerative endodontics. A scaffold must be safe, biodegradable, and biocompatible, with low immunogenicity, and must be able to support cell growth. Moreover, it must be supported by adequate scaffold characteristics, which include the level of porosity, pore size, and interconnectivity; these factors ultimately play an essential role in cell behavior and tissue formation. The use of natural or synthetic polymer scaffolds with excellent mechanical properties, such as small pore size and a high surface-to-volume ratio, as a matrix in dental tissue engineering has recently received a lot of attention because it shows great potential with good biological characteristics for cell regeneration. This review describes the latest developments regarding the usage of natural or synthetic scaffold polymers that have the ideal biomaterial properties to facilitate tissue regeneration when combined with stem cells and growth factors in revitalizing dental pulp tissue. The utilization of polymer scaffolds in tissue engineering can help the pulp tissue regeneration process.

Insights into the aetiologies of hypercementosis: A systematic review and a scoring system

OBJECTIVES

This paper aims to better define hypercementosis, investigate its described potential aetiologies, and determine whether there are different patterns of cementum apposition and if they are a function of their supposed aetiology.

DESIGN

A literature review was undertaken using the Medline, DOSS, Scopus and Cochrane Library electronic databases. Two co-authors selected the published works independently, extracted the data in accordance with the PRISMA statement.

RESULTS

Among 546 articles, 75 articles were finally selected. Eight different supposed aetiologies were identified: (1) intensive masticatory effort, (2) systemic disease, (3) carious lesion and apical periodontitis, (4) impaction, (5) periodontal disease, (6) concrescence, (7) super-eruption, and (8) drugs. Some of these aetiologies can be combined in the same tooth. Hypercementosis manifestations are various in nature and extent with different patterns that may be aetiology-specific. To improve the description and associated consistency in the characterisation of hypercementosis, in this review but also in future studies, we propose a new qualitative scoring system to quickly characterise hypercementosis and determine its most relevant aetiology.

CONCLUSIONS

This systematic review demonstrates that hypercementosis is a complex and not yet well-defined condition. Some forms of apposition are specific to a given aetiology. The hypercementosis characterisation may contribute to document the oral condition and/or the individuals masticatory activity.

Lyophilized Progenitor Tenocyte Extracts: Sterilizable Cytotherapeutic Derivatives with Antioxidant Properties and Hyaluronan Hydrogel Functionalization Effects

Cultured primary progenitor tenocytes in lyophilized form were previously shown to possess intrinsic antioxidant properties and hyaluronan-based hydrogel viscosity-modulating effects in vitro. The aim of this study was to prepare and functionally characterize several stabilized (lyophilized) cell-free progenitor tenocyte extracts for inclusion in cytotherapy-inspired complex injectable preparations. Fractionation and sterilization methods were included in specific biotechnological manufacturing workflows of such extracts. Comparative and functional-oriented characterizations of the various extracts were performed using several orthogonal descriptive, colorimetric, rheological, mechanical, and proteomic readouts. Specifically, an optimal sugar-based (saccharose/dextran) excipient formula was retained to produce sterilizable cytotherapeutic derivatives with appropriate functions. It was shown that extracts containing soluble cell-derived fractions possessed conserved and significant antioxidant properties (TEAC) compared to the freshly harvested cellular starting materials. Progenitor tenocyte extracts submitted to sub-micron filtration (0.22 µm) and 60Co gamma irradiation terminal sterilization (5−50 kGy) were shown to retain significant antioxidant properties and hyaluronan-based hydrogel viscosity modulating effects. Hydrogel combination products displayed important efficacy-related characteristics (friction modulation, tendon bioadhesivity) with significant (p < 0.05) protective effects of the cellular extracts in oxidative environments. Overall, the present study sets forth robust control methodologies (antioxidant assays, H2O2-challenged rheological setups) for stabilized cell-free progenitor tenocyte extracts. Importantly, it was shown that highly sensitive phases of cytotherapeutic derivative manufacturing process development (purification, terminal sterilization) allowed for the conservation of critical biological extract attributes.

Natural monoterpenes-laden electrospun fibrous scaffolds for endodontic infection eradication

This investigation aimed to synthesize poly(D,L-lactide) (PLA)-based fibrous scaffolds containing natural essential oils (i.e., linalool and citral) and determine their antimicrobial properties and cytocompatibility as a clinically viable cell-friendly disinfection strategy for regenerative endodontics. PLA-based fibrous scaffolds were fabricated via electrospinning with different concentrations of linalool and citral. The micromorphology and average diameter of the fibers was investigated through scanning electron microscopy (SEM). The chemical composition of the scaffolds was inferred by Fourier-transform infrared spectroscopy (FTIR). Antimicrobial efficacy against Enterococcus faecalis and Actinomyces naeslundii was also evaluated by agar diffusion and colony-forming units (CFU) assays. The scaffolds' cytocompatibility was determined using dental pulp stem cells (DPSCs). Statistical analyses were performed and the significance level was set at α = 5%. Linalool and citral's incorporation in the PLA fibrous scaffolds was confirmed in the FTIR spectra. SEM images indicate no morphological changes upon inclusion of the essential oils, except the reduced diameter of 40% linalool-laden fibers (p < 0.05). Importantly, significant antimicrobial properties were reported for citral-containing scaffolds for CFU/mL counts (p < 0.05), while only 20% and 40% linalool-laden scaffolds reduced CFU/mL (p < 0.05). Meanwhile, the inhibition halos were verified in a concentration-dependent manner for all monoterpenes-laden scaffolds. Citral- and linalool-laden PLA-based fibrous scaffolds showed acceptable cytocompatibility. The incorporation of natural monoterpenes did not alter the scaffolds' fibrous morphology, promoted antimicrobial action against endodontic pathogens, and preserved DPSCs viability. Linalool- and citral-laden electrospun scaffolds hold promise as naturally derived antimicrobial therapeutics for applications in regenerative endodontics.

Influence of ethylenediaminetetraacetic acid irrigation on the regenerative endodontic procedure in an immature rat molar model

AIM

To analyse the influence of ethylenediaminetetraacetic acid (EDTA) on the repair process in immature rat molars after a regenerative endodontic procedure (REP).

METHODOLOGY

The lower first molars of 12 4-week-old Wistar rats underwent pulpectomy in the mesial root and were divided into the following groups: sodium hypochlorite (NaOCl; n = 6) - the mesial canals were irrigated with 2.5% NaOCl for 5 min, and NaOCl-EDTA (n = 6) - the canals were irrigated with 2.5% NaOCl, followed by 17% EDTA for 5 min each. After evoking bleeding using a size 10 K-file, the cavities were sealed. Three molars on the untreated side were randomly used as control (control-15 d; n = 3), and three molars from the other three rats untreated were used as immediate control (n = 3). After 15 days (NaOCl, NaOCl-EDTA and control-15 d groups) or immediately (control-immediate), the animals were euthanized, and the teeth were subjected to histologic evaluation of tissue regeneration and presence of collagen fibres. Mann-Whitney U-test was used (p < .05).

RESULTS

The experimental groups had newly formed cementum-like tissue and increased root length and thickness. Half of the specimens in NaOCl-EDTA group showed apical foramen closure, whilst the NaOCl group had partial apical closure. The experimental groups showed inflammatory infiltrate extending mainly to the medium third of the root canal. These parameters were similar between experimental groups (p > .05). Newly formed connective tissue in the pulp space was significantly higher in the NaOCl-EDTA group than in NaOCl group (p < .05). Regarding the collagen fibres, the NaOCl-EDTA group had more collagen fibres in the root tip, but there was no significant difference compared to NaOCl group, and both groups showed greater amount of immature fibres in this area; in the centre of the apical third of root canal, there was equivalence between mature and immature fibres from both groups (p > .05).

CONCLUSIONS

Ethylenediaminetetraacetic acid irrigation improved newly formed intracanal connective tissue after REP in immature molars of rats; however, EDTA did not influence cementum-like tissue formation, apical closure, inflammatory infiltrate and maturation of collagen fibres.

Development of Growth Factor Releasing Hyaluronic Acid-Based Hydrogel for Pulp Regeneration: A Preliminary Study

Growth factors play essential roles as signaling molecules in pulp regeneration. We investigated the effect of a hyaluronic acid (HA)-collagen hybrid hydrogel with controlled release of fibroblast growth factor (FGF)-2 and platelet-derived growth factor (PDGF)-BB on human pulp regeneration. The cell interaction and cytotoxicity of the HA-collagen hybrid hydrogel, the release kinetics of each growth factor, and the effects of the released growth factors on pulp cell proliferation were examined. The vitality of pulp cells was maintained. The amounts of FGF-2 and PDGF-BB released over 7 days were 68% and 50%, respectively. Groups with a different concentration of growth factor (FGF-2: 100, 200, 500, and 1000 ng/mL; PDGF-BB: 10, 50, 100, 200, and 500 ng/mL) were experimented on days 1, 3, 5, and 7. Considering FGF-2 concentration, significantly increased pulp cell proliferation was observed on days 1, 3, 5, and 7 in the 100 ng/mL group and on days 3, 5, and 7 in the 200 ng/mL group. In the case of PDGF-BB concentration, significantly increased pulp cell proliferation was observed at all four time points in the 100 ng/mL group and on days 3, 5, and 7 in the 50, 200, and 500 ng/mL groups. This indicates that the optimal concentration of FGF-2 and PDGF-BB for pulp cell proliferation was 100 ng/mL and that the HA-collagen hybrid hydrogel has potential as a controlled release delivery system for FGF-2 and PDGF-BB.

Biomimetic Approaches in Clinical Endodontics

In the last few decades, biomimetic concepts have been widely adopted in various biomedical fields, including clinical dentistry. Endodontics is an important sub-branch of dentistry which deals with the different conditions of pulp to prevent tooth loss. Traditionally, common procedures, namely pulp capping, root canal treatment, apexification, and apexigonesis, have been considered for the treatment of different pulp conditions using selected materials. However, clinically to regenerate dental pulp, tissue engineering has been advocated as a feasible approach. Currently, new trends are emerging in terms of regenerative endodontics which have led to the replacement of diseased and non-vital teeth into the functional and healthy dentine-pulp complex. Root- canal therapy is the standard management option when dental pulp is damaged irreversibly. This treatment modality involves soft-tissue removal and then filling that gap through the obturation technique with a synthetic material. The formation of tubular dentine and pulp-like tissue formation occurs when stem cells are transplanted into the root canal with an appropriate scaffold material. To sum up tissue engineering approach includes three components: (1) scaffold, (2) differentiation, growth, and factors, and (3) the recruitment of stem cells within the pulp or from the periapical region. The aim of this paper is to thoroughly review and discuss various pulp-regenerative approaches and materials used in regenerative endodontics which may highlight the current trends and future research prospects in this particular area.

Regeneration of the Pulp Tissue: Cell Homing versus Cell Transplantation Approach: A Systematic Review

BACKGROUND

The main objective of this systematic review was to compare the apical healing, root maturation and histological characteristics of teeth treated with cell-based versus cell-free techniques.

METHODS

The methodology of this review was based on the PRISMA (Preferred Reporting Items for Systematic Reviews and Meta-Analyses) guidelines. A literature search strategy was carried out on PubMed, EMBASE and the Web of Science databases. The last search was done on 1 August 2021. Articles written in languages other than English were excluded. Two researchers independently selected the studies and extracted the data. As no randomized clinical trials were available, animal studies were included.

RESULTS

In total, 26 studies were included in the systematic review: 22 articles only researched the cell-free technique, 3 articles compared the cell-based to the cell-free technique, and 1 article compared the cell-based technique to apexification. In terms of apical healing, qualitative analysis of the data suggested that there seems to be no significant difference between cell-free and cell-based techniques. The results regarding tooth maturation are contradictory. The main difference between the cell-free and the cell-based techniques seems to be the histology of the treated tooth. The cell-free technique seems to result in cementum-like, bone-like or periodontal ligament-like tissue. One study, on the other hand, found that the cell-based technique resulted in regeneration of the whole pulp with an odontoblast layer, connective tissue, blood vessels and neuronal tissue.

CONCLUSIONS

Currently, the number of randomized clinical trials on this topic are very scarce. This is probably due to the limited infrastructure and lack of resources to apply the cell-based technique. Even though both techniques seem to be promising for clinical application, long-term data need to be provided regarding the healing and reparative patterns.

Regenerative endodontic therapy for external inflammatory lateral resorption following traumatic dental injuries: Evidence assessment of best practices

BACKGROUND

External inflammatory lateral resorption (EILR) following dental trauma is a severe complication that can lead to significant root loss and tooth extraction.

OBJECTIVE

The aim of this project was to review current evidence in the literature on regenerative endodontic therapy (RET) for EILR following traumatic injuries and assess the best treatment practices.

METHODS

Publications appearing in PubMed, from January 1, 2001 to January 9, 2022 were studied. Inclusion criteria were: (a) Publications in English; (b) Publications on RET and EILR; (c) Teeth subjected to dental trauma; and (d) Presence of intracanal bleeding and blood clots. Exclusion criteria were: (a) Conference proceedings; (b) Lectures; (c) Abstracts; and (d) Letters to editor; (e) Non-English publications.

RESULTS

355 publications were analysed. Nine met all inclusion criteria. In 10 (58.8%) teeth, triple antibiotic paste was used for an average of 26 days. Double antibiotic paste was used in 3 (17.6%) teeth for an average of 14 days. In 3 (17.6%) cases, calcium hydroxide (Ca(OH)₂ ) was used for 14 days and negative pressure irrigation was applied once on 1 (6%) tooth.

DISCUSSION

Using RET to treat EILR has some advantages compared to long term CA(OH)₂ dressing. RET requires shorter dressing time compared to CA(OH)₂ . This can significantly improve patient compliance. Additionally, in immature teeth, RET helps to arrest root resorption leading to continued root maturogenesis and revascularization. It is recommended that a meticulous follow-up should be conducted when RET is performed to assure early detection of treatment failure.

CONCLUSIONS

RET appears to be a good treatment modality producing biologic repair and improving prognosis in cases of EILR in post-traumatic tooth/pulp injuries. The key limitation of this study is that all publications included were either case reports or case series that usually tend to report successful outcome.

The Four Pillars for Successful Regenerative Therapy in Endodontics: Stem Cells, Biomaterials, Growth Factors, and Their Synergistic Interactions

Endodontics has made significant progress in regenerative approaches in recent years, thanks to advances in biologically based procedures or regenerative endodontic therapy (RET). In recent years, our profession has witnessed a clear conceptual shift in this therapy. RET was initially based on a blood clot induced by apical bleeding without harvesting the patient’s cells or cell-free RET. Later, the RET encompassed the three principles of tissue engineering, stromal/stem cells, scaffolds, and growth factors, aiming for the regeneration of a functional dentin pulp complex. The regenerated dental pulp will recover the protective mechanisms including innate immunity, tertiary dentin formation, and pain sensitivity. This comprehensive review covers the basic knowledge and practical information for translational applications of stem cell-based RET and tissue engineering procedures for the regeneration of dental pulp. It will also provide overall information on the emerging technologies in biological and synthetic matrices, biomaterials, and signaling molecules, recent advances in stem cell therapy, and updated experimental results. This review brings useful and timely clinical evidence for practitioners to understand the challenges faced for a successful cell-based RET and the importance of preserving or reestablishing tooth vitality. The clinical translation of these current bioengineering approaches will undoubtedly be beneficial to the future practice of endodontics.

Tissue Characteristics in Endodontic Regeneration: A Systematic Review

The regenerative endodontic procedure (REP) represents a treatment option for immature necrotic teeth with a periapical lesion. Currently, this therapy has a wide field of pre-clinical and clinical applications, but no standardization exists regarding successful criteria. Thus, by analysis of animal and human studies, the aim of this systematic review was to highlight the main characteristics of the tissue generated by REP. A customized search of PubMed, EMBASE, Scopus, and Web of Science databases from January 2000 to January 2022 was conducted. Seventy-five human and forty-nine animal studies were selected. In humans, the evaluation criteria were clinical 2D and 3D radiographic examinations. Most of the studies identified a successful REP with an asymptomatic tooth, apical lesion healing, and increased root thickness and length. In animals, histological and radiological criteria were considered. Newly formed tissues in the canals were fibrous, cementum, or bone-like tissues along the dentine walls depending on the area of the root. REP assured tooth development and viability. However, further studies are needed to identify procedures to successfully reproduce the physiological structure and function of the dentin–pulp complex.

Photocrosslinkable methacrylated gelatin hydrogel as a cell-friendly injectable delivery system for chlorhexidine in regenerative endodontics

OBJECTIVES

This work sought to formulate photocrosslinkable chlorhexidine (CHX)-laden methacrylated gelatin (CHX/GelMA) hydrogels with broad spectrum of action against endodontic pathogens as a clinically viable cell-friendly disinfection therapy prior to regenerative endodontics procedures.

METHODS

CHX/GelMA hydrogel formulations were successfully synthesized using CHX concentrations between 0.12 % and 5 % w/v. Hydrogel microstructure was evaluated by scanning electron microscopy (SEM). Swelling and enzymatic degradation were assessed to determine microenvironmental effects. Compression test was performed to investigate the influence of CHX incorporation on the hydrogels' biomechanics. The antimicrobial and anti-biofilm potential of the formulated hydrogels were assessed using agar diffusion assays and a microcosms biofilm model, respectively. The cytocompatibility was evaluated by exposing stem cells from human exfoliated deciduous teeth (SHEDs) to hydrogel extracts (i.e., leachable byproducts obtained from overtime hydrogel incubation in phosphate buffer saline). The data were analyzed using One- and Two-way ANOVA and Tukey's test (α = 0.05).

RESULTS

CHX/GelMA hydrogels were effectively prepared. NMR spectroscopy confirmed the incorporation of CHX into GelMA. The addition of CHX did not change the micromorphology (pore size) nor the swelling profile (p > 0.05). CHX incorporation reduced the degradation rate of the hydrogels (p < 0.001); whereas, it contributed to increased compressive modulus (p < 0.05). Regarding the antimicrobial properties, the incorporation of CHX showed a statistically significant decrease in the number of bacteria colonies at 0.12 % and 0.5 % concentration (p < 0.001) and completely inhibited the growth of biofilm at concentration levels 1 %, 2 %, and 5 %. Meanwhile, the addition of CHX, regardless of the concentration, did not lead to cell toxicity, as cell viability values were above 70 %.

SIGNIFICANCE

The addition of CHX into GelMA showed significant antimicrobial action against the pathogens tested, even at low concentrations, with the potential to be used as a cell-friendly injectable drug delivery system for root canal disinfection prior to regenerative endodontics.

Advanced biomaterials for periodontal tissue regeneration

The periodontium is a suitable target for regenerative intervention, since it does not functionally restore itself after disease. Importantly, the limited regeneration capacity of the periodontium could be improved with the development of novel biomaterials and therapeutic strategies. Of note, the regenerative potential of the periodontium depends not only on its tissue-specific architecture and function, but also on its ability to reconstruct distinct tissues and tissue interfaces, suggesting that the advancement of tissue engineering approaches can ultimately offer new perspectives to promote the organized reconstruction of soft and hard periodontal tissues. Here, we discuss material-based, biologically active cues, and the application of innovative biofabrication technologies to regenerate the multiple tissues that comprise the periodontium.

Advances in Scaffolds Used for Pulp-Dentine Complex Tissue Engineering - A Narrative Review

Pulp necrosis in immature teeth disrupts root development and predisposes roots to fracture as a consequence of their thin walls and open apices. Regenerative endodontics is a developing treatment modality whereby necrotic pulps are replaced with newly formed healthy tissue inside the root canal. Many clinical studies have demonstrated the potential of this strategy to stimulate root maturation and apical root-end closure. However, clinical outcomes are patient-dependent and unpredictable. The development of predictable clinical protocols is achieved through the interplay of the three classical elements of tissue engineering, namely, stem cells, signaling molecules, and scaffolds. Scaffolds provide structural support for cells to adhere and proliferate and also regulate cell differentiation and metabolism. Hence, designing and fabricating an appropriate scaffold is a crucial step in tissue engineering. In this review, four main classes of scaffolds used to engineer pulp-dentine complexes, including bioceramic-based scaffolds, synthetic polymer-based scaffolds, natural polymer-based scaffolds, and composite scaffolds, are covered. Additionally, recent advances in the design, fabrication, and application of such scaffolds are analysed along with their advantages and limitations. Finally, the importance of vascular network establishment in the success of pulp-dentine complex regeneration and strategies used to create scaffolds to address this challenge are discussed.

Poly(Caprolactone)-Aligned Nanofibers Associated with Fibronectin-loaded Collagen Hydrogel as a Potent Bioactive Scaffold for Cell-Free Regenerative Endodontics

AIM

Guided tissue regeneration has been considered a promising strategy to replace conventional endodontic therapy of teeth with incomplete root formation. Therefore, the objective of this study was to develop a tubular scaffold (TB-SC) with poly (caprolactone)-aligned nanofibers associated with a fibronectin-loaded collagen hydrogel and assess the pulp regeneration potential mediated by human apical papilla cells (hAPCs) using an in vitro model of teeth with incomplete root formation.

METHODOLOGY

Aligned nanofiber strips based on 10% poly(caprolactone) (PCL) were synthesized with the electrospinning technique to produce the TB-SCs. These were submitted to different treatments, according to the following groups: TB-SC (negative control): TB-SC without treatment; TB-SC+FN (positive control): TB-SC coated with 10 μg/mL of fibronectin; TB-SC+H: TB-SC associated with collagen hydrogel; TB-SC+HFN: TB-SC associated with fibronectin-loaded collagen hydrogel. Then, the biomaterials were inserted into cylindrical devices to mimic the regenerative therapy of teeth with incomplete root formation. The hAPCs were seeded on the upper surface of the TB-SCs associated or not with any treatment, and cell migration/proliferation and the gene expression of markers related to pulp regeneration (ITGA5, ITGAV, COL1A1, and COL1A3) were evaluated. The data were submitted to ANOVA/Tukey's tests (α=5 %).

RESULTS

Higher values of cell migration/proliferation and gene expression of all markers tested were observed in groups TB-SC+FN, TB-SC+H, and TB-SC+HFN compared with the TB-SC group (p<0.05). The hAPCs in the TB-SC+HFN group showed the highest values of cell proliferation and gene expression of COL1A1 and COL3A1 (p<0.05), as well as superior cell migration results to groups TB-SC and TB-SC+H (p<0.05).

CONCLUSION

Aligned nanofiber scaffolds associated with the fibronectin-loaded collagen hydrogel enhanced the migration and proliferation of hAPCs, and gene expression of pulp regeneration markers. Therefore, the use of these biomaterials may be considered an interesting strategy for regenerative pulp therapy of teeth with incomplete root formation.

Effect of Duration of Root Canal Infection on the Ability of Dentin-Pulp Complex Regeneration of Immature Permanent Teeth: An Animal Study

BACKGROUND

Persistent infection is always considered the most important reason for the failure of dentin-pulp complex regeneration. The present study aims to evaluate the effect of the duration of root canal infection (from one to twelve weeks) on the ability of dentin-pulp complex regeneration.

METHODS

In this animal study, 64 roots of immature premolar teeth of four dogs were randomly divided into four groups. Positive control group; eight root canals treated with regenerative endodontic procedure (REP), negative control group; 12 infected root canals, intervention groups; 36 root canals infected with supragingival plaque (one, three, six, and 12 weeks) and treated with REP, an additional positive control group; eight normal roots. After three months, the teeth were investigated by radiographic images and immunohistochemical staining (CD31, CD34, S100 markers). In addition, DSPP gene expression was assessed using a real-time PCR technique. The results were analyzed at a significance level of 0.05.

RESULTS

Based on radiological evaluation among the intervention groups, the highest root canal development (length and width) occurred in the intervention group of one week, and the lowest radiological results were in the intervention groups of six and 12 weeks (One-way ANOVA, P <0.05). There was a significant difference between the groups in terms of CD31, CD34, S100 and, DSPP expression percentage (One-way ANOVA, P <0.05), in which the highest and lowest expression percentages belonged to the one- and 12 weeks groups, respectively, among the intervention groups.

CONCLUSION

This study demonstrated that long root canal infection decreased the ability of the body to regenerate dentin-pulp complex.

Long-term outcome of nonvital immature permanent teeth treated with apexification and corono-radicular adhesive restoration - a case series

INTRODUCTION

This study aims to evaluate the long-term outcome of sixteen permanent maxillary central incisors with nonvital pulps and open apices treated with apexification and corono-radicular adhesive restorations, within a follow-up span of 5 to 22 years.

METHODS

Fourteen patients providing a total of sixteen teeth treated with MTA (n = 12), Biodentine (n = 3) or β-tricalcium phosphate (n = 1) apical barrier and corono-radicular restoration, with or without fiberglass post, were included. Clinical and radiographic criteria were defined for assessment at recall. Restoration and periapical tissues' status evaluation were performed according to FDI World Dental Federation's esthetic, functional and biological criteria and Ørstavik Periapical Index (PAI). Outcome was dichotomized in "healed" (PAI ≤ 2, asymptomatic with absence of signs of infection) or "not healed" (PAI ≥ 3, presence of clinical signs and/or symptoms).

RESULTS

Fourteen out of twenty-four patients were available for the present study (recall rate = 58%). Within a follow-up of 5 to 22 years, ten (62.5%) teeth were considered "healed", fulfilling both strict clinical and radiographic success criteria. Only one tooth was missing due to root resorption and one patient was presenting with clinical signs and symptoms at recall, resulting in a survival rate of 93.8%.

CONCLUSIONS

Adhesive corono-radicular restoration in nonvital permanent immature teeth treated with apexification allows for favorable long-term outcomes, by ensuring structural reinforcement and coronal microleakage prevention. Teeth sustaining a substantial loss of coronal structure may require post/core placement. In the case of failure, this endodontic-restorative combination assured teeth survival until growth phase conclusion, thus allowing for proper prosthetic rehabilitation approaches.

Histological Evaluation of Restylane Lyft Used as a Scaffold for Dental Pulp Regeneration in Non-Infected Immature Teeth in Dogs

Commercially available hyaluronic acid dermal fillers used as a scaffold in regenerative endodontic procedures (REPs) have demonstrated attractive potentials. This study aimed to histologically evaluate the outcome of REPs using Restylane Lyft (HA) as a scaffold. REPs were performed on pulpless, immature roots in dogs (n = 69). The roots were divided into four groups: blood clot (BC), Restylane Lyft (BC + HA), negative control, and positive control. At 13 weeks postoperatively, hard tissue formation, vascularization, the presence of vascularized soft connective tissue and collagen fibers, the degree of inflammation within pulp spaces and/or periapical tissues, and apical closure were evaluated histologically. The vascularization and formation of loosely arranged collagen fibers within the regenerated soft connective tissues were observed significantly more in the BC+HA group (85% and 40%, respectively; p < 0.05) compared to the BC group (54.6% and 9.1%, respectively; p < 0.05). The degree of inflammation was significantly higher in the HA group than in the BC group; moderate to severe inflammatory cell infiltration was seen in 45% and 13.6% of the cases, respectively. The results of the present study suggest that Restylane Lyft combined with a blood clot used as a scaffold may improve the outcomes of REPs in non-infected, pulpless, immature teeth in dogs.

Biomaterial scaffolds for clinical procedures in endodontic regeneration

Regenerative endodontic procedures have been rapidly evolving over the past two decades and are employed extensively in clinical endodontics. These procedures have been perceived as valuable adjuvants to conventional strategies in the treatment of necrotic immature permanent teeth that were deemed to have poor prognosis. As a component biological triad of tissue engineering (i.e., stem cells, growth factors and scaffolds), biomaterial scaffolds have demonstrated clinical potential as an armamentarium in regenerative endodontic procedures and achieved remarkable advancements. The aim of the present review is to provide a broad overview of biomaterials employed for scaffolding in regenerative endodontics. The favorable properties and limitations of biomaterials organized in naturally derived, host-derived and synthetic material categories were discussed. Preclinical and clinical studies published over the past five years on the performance of biomaterial scaffolds, as well as current challenges and future perspectives for the application of biomaterials for scaffolding and clinical evaluation of biomaterial scaffolds in regenerative endodontic procedures were addressed in depth.

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Overview of biomaterials for scaffolding in regenerative endodontics are presented.

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Findings of preclinical and clinical studies on the performance of biomaterial scaffolds are summarized.

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Challenges and future prospects in biomaterial scaffolds are discussed.