Dental Follicle Research Articles

Stem Cells: Innovations, Applications, and Future Directions

ABSTRACT Stem cells offer great promise in dentistry by regenerating critical oral tissues. Derived from sources such as dental pulp, periodontal ligament, and dental follicle, these cells can be pluripotent or multipotent and are capable of differentiating into various cell types, including odontoblasts and osteoblasts. This regenerative potential could transform treatments for dental conditions like periodontal disease and pulpitis. Advancing this field requires understanding stem cell differentiation and exploring tissue engineering and biomaterial scaffolds. Despite the potential, evolving legal and ethical issues shape the integration of these innovations. Research in dental stem cells represents a significant advance in regenerative medicine, promising to enhance dental treatments and patient care.

Histone H3K9 Methylation Is Differentially Modified in Odontogenic Cyst and Tumors.

Histone modification in odontogenic lesions is mostly unexplored. Trimethylation of histone H3 at lysine residue 9 (H3K9Me3) has been studied in various pathologic conditions and showed biological significance promising for future therapeutic application. This study aimed to investigate the level and clinical relevance of the H3K9Me3 histone modification in odontogenic cysts and tumors. A total of 105 cases of odontogenic lesions, comprising 30 odontogenic keratocysts (OKCs), 30 adenomatoid odontogenic tumors (AOTs), 30 ameloblastomas, and 15 dental follicles, were included in the study. The paraffin-embedded tissues were immunohistochemically stained for H3K9Me3. Both the intensity and the distribution of staining were evaluated and calculated as H-score. The correlation between the H3K9Me3 expression and the clinical characteristics of each lesion was evaluated. The Kruskal-Wallis test followed by Bonferroni's correction was performed to assess the differences in H-score among groups. In addition, Pearson's chi-squared test or Mann-Whitney U test was used to analyze potential factors that could affect protein expression. The reduced enamel epithelium of the dental follicle showed uniformly strong H3K9Me3 expression. All odontogenic cysts and tumors examined demonstrated a significantly reduced H3K9Me3 level compared with dental follicles. The AOT showed the lowest H3K9Me3 level, followed by OKC and ameloblastoma. Its immunoreactivity was mainly localized in the basal and parabasal cells of OKC and the whorled/duct-like structures of AOT. Ameloblastoma exhibited marked variation in the H3K9Me3 level among cases. Notably, the upregulated H3K9Me3 was related to multilocularity of OKC and ameloblastoma. Histone H3K9 methylation is differentially expressed in odontogenic cysts and tumors. This epigenetic modification may contribute to the pathogenesis and aggressive behavior of odontogenic lesions.

Eruption Cyst: A Case Report

An eruption cyst (EC) is a benign, nonodontogenic lesion. It appears as a Semi-spherical swelling in the mucosa overlying an erupting tooth. This condition occurs when the dental follicle separates from the crown, leading to the formation of a fluid-filled space. Eruption cysts usually have an epithelial lining and are encased in fibrous connective tissue. In a case involving an eleven-year-old girl, a painless, dome-shaped swelling was observed in the lower left posterior region of her jaw. This was diagnosed as an eruption cyst associated with tooth 35. An inferior alveolar nerve block was administered under local anesthesia. An access opening on tooth 75 was made and horizontal incision was given to drain the cystic fluid. Post-operative care included antibiotics and pain management. Follow-up visits showed significant healing, and subsequently pulpectomy and placement of a stainless-steel crown on tooth 75 was carried out. This case highlights the importance of conservative management for eruption cysts in pediatric patients, ensuring effective treatment while minimizing discomfort.

Human dental mesenchymal stem cells restorate immune response in sera of pemphigus vulgaris patients.

Pemphigus is an IgG-mediated autoimmune condition characterized by autoantibodies targeting desmogleins, leading to acantholysis. Current treatments, including systemic corticosteroids and immunosuppressive drugs, are associated with significant adverse effects. Mesenchymal stem cells (MSCs) offer a promising alternative due to their immunomodulatory properties and low immunogenicity. This study evaluates the immunomodulatory effects of dental follicle mesenchymal stem cells (DF-MSCs) obtained from healthy donors on Pemphigus vulgaris (PV) patients and healthy controls by examining T-cell proliferation, apoptosis, cytokine levels, and anti-desmoglein 1/3 IgG profiles. Peripheral blood mononuclear cells (PBMCs) were isolated from twenty-one symptomatic PV patients and eleven healthy volunteers. DF-MSCs were characterized and differentiated into osteocytes, adipocytes, and chondrocytes. Peripheral blood mononuclear cells (PBMCs) were co-cultured with DF-MSCs, and various assays were conducted to evaluate T-cell proliferation, apoptosis, regulatory T cells, cytokine expression, and autoantibody levels. Results showed that DF-MSC co-cultures significantly reduced lymphocyte proliferation (43.58-16.27%), IL-4 (38.06 ng/L to 32.26 ng/L), TNF-α (32.45 ng/L to 29.41 ng/L), and DSG1 (3.29 ng/ml to 3.00 ng/ml) and DSG3 (262.40 ng/ml to 245.08 ng/ml) levels in PV patients. An increase in regulatory T cells (1.22-3.75%), IL-10 (47.46 pg/ml to 54.94 pg/ml), and IFN-γ (12.39 ng/ml to 19.70 ng/ml) was also observed. No significant changes were noted in healthy controls. These findings suggest that DF-MSCs could potentially offer a curative approach for treating pemphigus by restoring immune balance. However, further clinical trials are necessary to confirm their efficacy.

Synthesis, Characterization and Osteogenic Properties of Chitin-Polydioxanone Composite Gel.

In this study, we have developed a Chitin(Ch)-Poly(dioxanone)(PDO) gel system, which can be potentially used for tissue engineering. Hydrogel has been widely used in biomedical applications for its tuneable properties and biocompatibility. Chitin (Ch) is a natural biopolymer used for its ability to mimic the natural extracellular matrix due to N-acetyl glucosamine structural units. Poly (dioxanone) (PDO) is an FDA-approved synthetic biopolymer known for its mechanical properties, good biocompatibility, and poor inflammatory response. Based on this, we have developed Ch-PDO composite gel using simple regeneration chemistry and characterized it using FT-IR and SEM. The developed composite gel showed improved gel strength, good swelling ability,and controlled degradation behaviour. It also showed good injectability with shear thinning properties and hemocompatibility. Further, the biocompatibility and cell adhesion studies of the prepared gels were studied using dental follicle stem cells (DFSCs). The prepared Ch-PDO gel was biocompatible and showed DFSCs cell attachment. Osteogenic mineralization and RUNX2 expression of the prepared Ch and Ch-PDO gel was studied and Ch-PDO gel showed an enhanced mineralization and RUNX2 expression. Therefore, the developed chitin-PDO gel could be potentially used for bone tissue engineering.

Single-cell RNA-seq analysis of rat molars reveals cell identity and driver genes associated with dental mesenchymal cell differentiation

BackgroundThe molecular mechanisms and signaling pathways involved in tooth morphogenesis have been the research focus in the fields of tooth and bone development. However, the cell population in molars at the late bell stage and the mechanisms of hard tissue formation and mineralization remain limited knowledge.ResultsHere, we used the rat mandibular first and second molars as models to perform single-cell RNA sequencing (scRNA-seq) analysis to investigate cell identity and driver genes related to dental mesenchymal cell differentiation during the late bell hard tissue formation stage. We identified seven main cell types and investigated the heterogeneity of mesenchymal cells. Subsequently, we identified novel cell marker genes, including Pclo in dental follicle cells, Wnt10a in pre-odontoblasts, Fst and Igfbp2 in periodontal ligament cells, and validated the expression of Igfbp3 in the apical pulp. The dynamic model revealed three differentiation trajectories within mesenchymal cells, originating from two types of dental follicle cells and apical pulp cells. Apical pulp cell differentiation is associated with the genes Ptn and Satb2, while dental follicle cell differentiation is associated with the genes Tnc, Vim, Slc26a7, and Fgfr1. Cluster-specific regulons were analyzed by pySCENIC. In addition, the odontogenic function of driver gene TNC was verified in the odontoblastic differentiation of human dental pulp stem cells. The expression of osteoclast differentiation factors was found to be increased in macrophages of the mandibular first molar.ConclusionsOur results revealed the cell heterogeneity of molars in the late bell stage and identified driver genes associated with dental mesenchymal cell differentiation. These findings provide potential targets for diagnosing dental hard tissue diseases and tooth regeneration.

RESSECÇÃO DE AMELOBLASTOMAS CONVENCIONAIS APÓS TRATAMENTO CONSERVADOR E RELATO DE TRANSFORMAÇÃO PERIFÉRICA: SÉRIE DE CASOS E REVISÃO INTEGRATIVA

Introduction: Ameloblastoma is a slow-growing tumor, presenting bone expansion and high recurrence rates. It originates from the tooth enamel, dental follicle, periodontal ligament or lining of odontogenic cysts and odontogenic epithelium. Recently, in 2022, the WHO reclassified ameloblastomas into conventional, unicystic, peripheral and metastatic due to prospective views based on updates to genetic studies, which has generated a dilemma in the literature regarding the ideal therapeutic approach for conventional ameloblastoma, to provide a lower surgical risk and morbidity to patients. Purpose: Carry out an integrative review of the literature, describing 02 resections of conventional ameloblastomas after conservative treatment and 01 report of peripheral transformation, providing valuable information on management. Methodology: The current study was divided into two stages. The first step consists in a descriptive series of three cases of conventional ameloblastomas treated by conservative methods, where two of them were subsequently submitted to partial resection and the third one turned into a peripheral ameloblastoma. In the second step, an integrative and systematic review was carried out in accordance with the PRISMA recommendations on resection and excision for treating conventional ameloblastomas. Results: Classification and treatment methods in cases of ameloblastoma are based on histopathological characteristics and can range from enucleation to resection with reconstruction. This study focuses on three case reports of patients with conventional ameloblastoma. The treatment consisted in two partial resections with primary reconstructions and one enucleation combined with a peripheral osteotomy after conservative treatments without prolonged follow-up. The treatment of choice and recurrence were evaluated, and the patients had satisfactory results. Conclusion: There is no consensus on the treatment of ameloblastomas. Both conservative surgeries and radical interventions are used. The chosen treatment must take into account the location of the tumor, size, age, general health condition and cooperation of the patient, possibility of long-term delivery, histopathological pattern and professional experience.

Xenogenous implanted dental follicle stem cells promote periodontal regeneration through inducing the N2 phenotype of neutrophils

BackgroundPeriodontal tissue loss is the main reason for tooth mobility and loss caused by periodontal disease. Dental follicle stem cells (DFSCs) have significant therapeutic potential in periodontal regeneration, which maybe mainly depends on their potent immunomodulatory capacity. Consequently, this study aims to elucidate the impact of implanted xenogenous DFSCs on innate immune responses during early and late stages in the periodontal defect repair period.MethodsTo trace and investigate the immunomodulation mechanisms of DFSCs in vivo, DFSCs were engineered (E-DFSCs) using lentiviral vectors expressing CD63-enhanced green fluorescent protein (CD63-EGFP) and β-Actin-mCherry protein (ACTB-mCherry) to exhibit green and red fluorescence. The biological characteristics and functions of E-DFSCs were verified by proliferation, differentiation, and co-culture experiments in vitro. In vivo, the periodontal regeneration capacity of E-DFSCs was detected by implantation of murine periodontal defect model, and the response of innate immune cells was detected at the 1st, 3rd, and 5th days (early stage) and 4th week (late stage) after implantation.ResultsIn vitro assessments showed that E-DFSCs retain similar properties to their non-engineered counterparts but exhibit enhanced macrophage immunomodulation capability. In mice models, four-week micro-CT and histological evaluations indicated that E-DFSCs have equivalent efficiency to DFSCs in periodontal defect regeneration. At the early stage of repair in mice periodontal defect, fluorescence tracking showed that implanted E-DFSCs might primarily activate endogenous cells through direct contact and indirect actions, and most of these cells are myeloperoxidase-positive neutrophils. Additionally, compared with the control group, the neutrophilic infiltration and conversion of N2-type were significantly increased in the E-DFSC group. At the late stage of defect regeneration, more M2-type macrophages, fewer TRAP + osteoclasts, and an upregulated OPG/RANKL ratio were detected in the E-DFSC group compared to the control group, which indicated that immune balance tilts towards healing and bone formation.ConclusionThe xenogenous implanted DFSCs can induce the N2 phenotype of neutrophils in the early stage, which can activate the innate immune mechanism of the host to promote periodontal tissue regeneration.

Melatonin-coated nanofiber cell sheets promote periodontal regeneration through ROS scavenging and preservation of stemness

Mesenchymal stem cell (MSC)-based cell sheet engineering holds great promise for periodontal tissue engineering and restoring damaged tissues. However, achieving optimal regenerative outcomes remains a challenge. This study introduces a novel approach that integrates melatonin-coated nanofiber fragments (mNFs) into dental follicle stem cell sheets (mNF-CSs) to enhance their regenerative potential. The mNF-CSs were engineered using electrospun poly-L-lactic acid (PLLA) nanofiber sheets fragmented into mNFs and coated with melatonin, a potent antioxidant and osteogenic agent. The mNF-CSs exhibited a homogenous morphology with sustained melatonin release over 21 days, providing a prolonged antioxidative effect critical for tissue regeneration. In vitro experiments demonstrated that mNF-CSs significantly reduced intracellular reactive oxygen species (ROS) levels and upregulated antioxidative proteins such as SOD1 and SOD2, resulting in improved cell viability, maintenance of stemness, and enhanced osteogenic differentiation potential of dental follicle stem cells (DFCs). In vivo studies using both a nude mouse and a rat periodontal defect model demonstrated that mNF-CSs promoted alveolar bone repair and periodontal tissue regeneration, with enhanced retention of MSCs at the defect site and increased expression of periodontal tissue-related markers. Transcriptome analysis revealed the upregulation of genes associated with biomineralization, odontogenesis, and autophagy pathways in mNF-CSs, suggesting their ability to modulate crucial cellular processes for tissue regeneration. Overall, mNF-CSs offer a promising strategy for enhancing periodontal tissue engineering applications, providing a platform for improving bone grafts and regenerative medicine strategies in the context of periodontal diseases.

Sclerostin inhibits Protein kinase C inhibitor GÖ6976 induced osteogenic differentiation of dental follicle cells

Human dental follicle cells (DFCs) as multipotent stem cells are currently investigated within the field of regenerative medicine considering their potential for the regeneration of dental tissues, bone defects caused by periodontal or degenerative diseases and the treatment of craniofacial disorders. However, molecular mechanisms of the differentiation into mineralizing cells are still inadequately understood. Previous studies have shown that GÖ6976, an inhibitor of classical isoforms of protein kinase C (PKC), enhanced ostogenic differentiation of DFCs. A possible mechanism for increased osteogenic differentiation could be the regulation of ossification inhibitors. This study therefore investigated whether the osteogenic differentiation inhibitor sclerostin (SOST) is regulated by GÖ6976 and whether the addition of sclerostin attenuates the stimulating effect of the PKC inhibitor. We demonstrated that the expression of the sclerostin gene decreased after PKC inhibition by GÖ6976 and that its gene expression is likely maintained by PKC via the BMP signaling pathway. Furthermore, supplementation of osteogenic differentiation medium with sclerostin impairs GÖ6976-induced differentiation of DFCs. Our data suggest that regulation of sclerostin mediates PKC inhibition-induced mineralization of DFCs.

Six1 Regulates Mouse Incisor Development by Promoting Dlx1/2/5 Expression

Tooth development is a complex process orchestrated by intricate gene regulatory networks, involving both odontogenic epithelium and ectomesenchyme. Six1, a pivotal transcription factor (TF), is involved in the development of the lower incisor. However, its precise role during incisor development and the molecular mechanisms underpinning its regulatory functions remain poorly understood. This study employs Six1 deletion mouse models to elucidate the critical regulatory role of Six1 in governing dental mesenchyme development. By performing single-cell RNA sequencing, we constructed a comprehensive transcriptome atlas of tooth germ development from the bud to bell stage. Our analyses suggest that the dental follicle and the dental papilla (DP) are differentiated from dental ectomesenchyme (DEM) and identify the key TFs underlying these distinct states. Notably, we show that Dlx1, Dlx2, and Dlx5 (Dlx1/2/5) may function as the key TFs that promote the formation of DP. We further show that the deletion of Six1 perturbs dental mesenchyme development by impeding the transitions from DEM to DP states. Importantly, SIX1 directly binds to the promoters of Dlx1/2/5 to promote their co-expression, which subsequently leads to widespread epigenetic and transcriptional remodeling. In summary, our findings unveil Six1’s indispensable role in incisor development, offering key insights into TF-driven regulatory networks that govern dental mesenchyme cell fate transitions during tooth development.

A Comparison of Immunohistochemical Expression of Epidermal Growth Factor Receptor and Human Epidermal Growth Factor Receptor 2 in Dental Follicles with Different Radiographic Sizes.

Odontogenic cysts and tumors develop from the dental follicle of asymptomatic impacted teeth. Odontogenic tissues express the epidermal growth factor receptor family (EGFR), which mediates cell proliferation, survival, and neoplastic differentiation. The present study aimed to compare the immunohistochemical expression of EGFR and human epidermal growth factor receptor 2 (HER2) in the dental follicle of impacted wisdom teeth with normal and abnormal radiographic size. In this analytical study, immunohistochemical staining of EGFR and HER2 was performed on 30 normal and 30 abnormal follicles of impacted third molars. Follicles with a width of <2.5 mm were considered normal, whereas those with a width of ≥2.5 mm were regarded as abnormal. The immunoreactive score (IRS) was used to report the expression levels of EGFR and HER2. The obtained data were analyzed using SPSS software. Age and sex were compared in normal and abnormal groups with independent t test and Chi square test, respectively. P<0.05 was considered statistically significant. The EGFR and HER2 overall expression was high in all normal and abnormal follicles. The comparison of the percentage of stained cells and intensity of EGFR and HER2 staining in normal and abnormal follicles were not significantly different (P=0.73, P=0.63, P=0.95, respectively). Due to the high expression of EGFR and HER2 in normal and abnormal follicles, as well as the lack of significant differences in these two groups, the radiographic size of dental follicles might not indicate the potential capabilities of their cells, and more research in this field is recommended.

Bone regeneration driven by a nano-hydroxyapatite/chitosan composite bioaerogel for periodontal regeneration.

The most recent progress in reconstructive therapy for the management of periodontitis and peri-implantitis bone defects has relied on the development of highly porous biodegradable bioaerogels for guided bone regeneration. The objective of this work was to evaluate in vitro the osteoinduction of periodontal-originating cells (human dental follicle mesenchymal cells, DFMSCs) promoted by a nano-hydroxyapatite/chitosan (nHAp/CS) bioaerogel, which was purified and sterilized by a sustainable technique (supercritical CO2). Moreover, the in vivo bone regeneration capacity of the nHAp/CS bioaerogel was preliminarily assessed as a proof-of-concept on a rat calvaria bone defect model. The quantification of DNA content of DFMSCs seeded upon nHAp/CS and CS scaffolds (control material) showed a significant increase from the 14th to the 21st day of culture. These results were corroborated through confocal laser scanning microscopy analysis (CLSM). Furthermore, the alkaline phosphatase (ALP) activity increased significantly on the 21st day, similarly for both materials. Moreover, the presence of nHAp promoted a significantly higher expression of osteogenic genes after 21days when compared to CS scaffolds and control. CLSM images of 21days of culture also showed an increased deposition of OPN over the nHAp/CS surface. The in vivo bone formation was assessed by microCT and histological analysis. The in vivo evaluation showed a significant increase in bone volume in the nHAp/CS test group when compared to CS and the empty control, as well as higher new bone formation and calcium deposition within the nHAp/CS structure. Overall, the present study showed that the nHAp/CS bioaerogel could offer a potential solution for periodontal and peri-implant bone regeneration treatments since the in vitro results demonstrated that it provided favorable conditions for DFMSC proliferation and osteogenic differentiation, while the in vivo outcomes confirmed that it promoted higher bone ingrowth.

Effect of residual dental follicle after removal of impacted mandibular third molar on the periodontal health of adjacent second molar

Objective: To investigate whether residual dental follicles in the alveolar socket after extraction of impacted mandibular third molars affect the periodontal health of adjacent mandibular second molars, in order to provide clinical reference for the management of residual dental follicles after third molar extraction. Methods: A total of 82 patients who underwent bilateral impacted mandibular third molar extraction at the Department of Oral Surgery, School and Hospital of Stomatology Wuhan University, from November 1, 2020, to November 30, 2022, were included in the study. Using a self-controlled method, each patient's bilateral mandibular third molars were randomly divided into two groups: Group A underwent third molar extraction with thorough removal of residual dental follicle tissue, while Group B underwent third molar extraction without any treatment of the remaining dental follicle tissue. Operation time and adverse reactions were recorded. Clinical and radiographic examinations were performed at 6-month follow-up to evaluate the periodontal parameters and alveolar bone height of the bilateral mandibular second molars, and differences between the two groups were compared. Results: All patients had successful bilateral mandibular third molar extractions, and no serious complications occurred intraoperatively or postoperatively. There were no statistically significant differences in surgical time, postoperative pain, or facial swelling between the two groups (P>0.05). At the 6-month follow-up, the probing depth on the distal aspect of the mandibular second molars in Group A [2.67 (2.00, 3.67) mm] was significantly less than that in Group B [4.00 (3.00, 5.00) mm] (Z=-6.55, P<0.001). The clinical attachment loss on the distal aspect of the mandibular second molars in Group A [1.00 (0.00, 3.00) mm] was less than that in Group B [3.00 (2.00, 5.00) mm] (Z=-5.99, P<0.001). The distance from the alveolar crest to the cementoenamel junction on the distal aspect of the mandibular second molars in Group A [(1.86±1.34) mm] was less than that in Group B [(3.04±1.89) mm] (t=6.87,P<0.001). In patients aged≥20 years, the probability of recovery of alveolar bone height to normal level on the distal aspect of the mandibular second molars in Group A [42.3% (11/26)] was significantly higher than that in Group B [0 (0/26)] (P<0.01), while there was no statistically significant difference between Group A [63.3% (19/30)] and Group B [46.7% (14/20)] in patients aged<20 years (P>0.05). Conclusions: Residual dental follicles in the alveolar socket after extraction of impacted mandibular third molars adversely affect the periodontal health of adjacent teeth. Thorough removal of residual dental follicles during impacted mandibular third molar extraction is beneficial for the postoperative recovery of alveolar bone height of the distal aspect of the mandibular second molars, especially in patients aged≥20 years.

Abnormal dental follicle cells: A crucial determinant in tooth eruption disorders (Review).

The dental follicle (DF) plays an indispensable role in tooth eruption by regulating bone remodeling through their influence on osteoblast and osteoclast activity. The process of tooth eruption involves a series of intricate regulatory mechanisms and signaling pathways. Disruption of the parathyroid hormone‑related protein (PTHrP) in the PTHrP‑PTHrP receptor signaling pathway inhibits osteoclast differentiation by DF cells (DFCs), thus resulting in obstructed tooth eruption. Furthermore, parathyroid hormone receptor‑1 mutations are linked to primary tooth eruption failure. Additionally, the Wnt/β‑catenin, TGF‑β, bone morphogenetic protein and Hedgehog signaling pathways have crucial roles in DFC involvement in tooth eruption. DFC signal loss or alteration inhibits osteoclast differentiation, affects osteoblast and cementoblast differentiation, and suppresses DFC proliferation, thus resulting in failed tooth eruptions. Abnormal tooth eruption is also associated with a range of systemic syndromes and genetic diseases, predominantly resulting from pathogenic gene mutations. Among these conditions, the following disorders arise due to genetic mutations that disrupt DFCs and impede proper tooth eruption: Cleidocranial dysplasia associated with Runt‑related gene 2 gene mutations; osteosclerosis caused by CLCN7 gene mutations; mucopolysaccharidosis type VI resulting from arylsulfatase B gene mutations; enamel renal syndrome due to FAM20A gene mutations; and dentin dysplasia caused by mutations in the VPS4B gene. In addition, regional odontodysplasia and multiple calcific hyperplastic DFs are involved in tooth eruption failure; however, they are not related to gene mutations. The specific mechanism for this effect requires further investigation. To the best of our knowledge, previous reviews have not comprehensively summarized the syndromes associated with DF abnormalities manifesting as abnormal tooth eruption. Therefore, the present review aims to consolidate the current knowledge on DFC signaling pathways implicated in abnormal tooth eruption, and their association with disorders of tooth eruption in genetic diseases and syndromes, thereby providing a valuable reference for future related research.

Gingival mesenchymal stem cells: Biological properties and therapeutic applications

Our understanding of mesenchymal stem cells (MSCs) and their biological properties is steadily increasing, with more studies focusing on their therapeutic effects in the domains of immunology, tissue engineering and regenerative medicine. MSCs may be derived from tissues such as bone marrow, adipose, the umbilical cord, as well as from dental tissues (e.g., tooth germ, dental follicle, pulp tissue of exfoliated deciduous and permanent teeth, apical papilla, periodontal ligament, gingiva, and alveolar bone). Gingival mesenchymal stem cells (GMSCs) are non-hematopoietic adult stem cells isolated from the gingival lamina propria. When compared to MSCs purified from various dental and non-dental tissues, GMSCs are more abundant in source, relatively non-invasive to obtain, and genetically stable. In recent years, many studies have found that GMSCs possess the ability of self-renewal, multi-directional differentiation, and chemotaxis to inflammatory sites for immunity regulation. Their molecular and stem-cell properties make them highly suitable for both preclinical and clinical research. Extracellular vesicles (EVs) secreted by GMSCs are of key interest due to their ability to emulate the biological and therapeutic activity of GMSCs themselves. This paper will therefore review the current consensus on GMSCs, surveying their sources and isolation methods, their biological properties, and their therapeutic applications on inflammatory and immune-related diseases.

Clinicial-pathologic correlations of non-trauma related Odontodysplasia in 28 dogs: 2013-2023.

Odontodysplasia is an uncommon dental developmental disorder associated with enamel, dentin, pulp abnormalities, and overall tooth morphology. The affected tooth is grossly abnormal in size and contour and is commonly associated with swelling of the affected area and failure of eruption. Histologically, the enamel and dentin are hypoplastic and hypomineralized. Odontodyplasia occurs most commonly in response to direct trauma to the developing tooth bud (enamel organ and dental follicle). Data on the prevalence and features of non-traumatic odontodysplasia are lacking. Medical records of dogs diagnosed with odontodysplasia were reviewed at the William R. Pritchard Veterinary Medical Teaching Hospital (VMTH), University of California, Davis, for 10 years (from 2013 to 2023). Dogs with a known history of facial trauma, persistent deciduous tooth or teeth over the region of odontodysplastic tooth or teeth, and endodontic disease of the persistent deciduous tooth or teeth were excluded from the study. Twenty-eight dogs were included in this retrospective study, representing an incidence of 1.4 per 100 dogs presenting over 10 years. Regional odontodysplasia (RO) was identified in twenty-two dogs, and generalized odontodysplasia (GO) was found in six dogs. Both comprehensive oral examination and diagnostic imaging were essential in diagnosing and assessing the presence of odontodysplasia. Awake oral examination failed to identify odontodysplasia in almost 70% of the RO cases. Secondary diseases or lesions in odontodysplastic teeth, such as periodontal disease, endodontal disease, and perio-endo lesions, were commonly seen and were particularly more frequently identified in strategic teeth (canine and carnassial teeth) than non-strategic ones. Similarities, such as female predilection, maxilla more commonly affected, and clinical signs, were observed between RO in dogs and those reported in people. The exact etiology of non-traumatic odontodysplasia remains elusive, and the condition may be of multifactorial causality.

High-yield nanovesicles extruded from dental follicle stem cells promote the regeneration of periodontal tissues as an alternative of exosomes.

To identify an optimized strategy for the large-scale production of nanovesicles (NVs) that preserve the biological properties of exosomes (EXOs) for use in periodontal regeneration. NVs from dental follicle stem cells (DFSCs) were prepared through extrusion, and EXOs from DFSCs were isolated. The yield of both extruded NVs (eNVs) and EXOs were quantified through protein concentration and particle number analyses. Their pro-migration, pro-proliferation and pro-osteogenesis capacities were compared subsequently in vitro. Additionally, proteomics analysis was conducted. To further evaluate the periodontal regeneration potential of eNVs and EXOs, they were incorporated into collagen sponges and transplanted into periodontal defects in rats. In vivo imaging and H&E staining were utilized to verify their biodistribution and safety. Micro-Computed Tomography analysis and histological staining were performed to examine the regeneration of periodontal tissues. The yield of eNVs was nearly 40 times higher than that of EXOs. Interestingly, in vitro experiments indicated that the pro-migration and pro-proliferation abilities of eNVs were superior, and the pro-osteogenesis potential was comparable to EXOs. More importantly, eNVs exhibited periodontal regenerative potential similar to that of EXOs. Extrusion has proven to be an efficient method for generating numerous eNVs with the potential to replace EXOs in periodontal regeneration.

Characteristics of Gubernacular Canal of Impacted/ Unerupted Canine in Relation to Eruption Status by Using CBCT

To evaluate detection rates and morphology of gubernacular canal (GC) in impacted/ unerupted canine, and to determine whether there is a difference in GC characteristics between impacted and unerupted canine. Subjects and Methods: By using CBCT, GCs were retrospectively analyzed in 300 patients with 432 impacted/ unerupted canine (96 males, 204 females; Age range, 7 to 54 years). Each imaging system software was first converted the CBCT pictures to volumetric data, from which reconstructions on multiple planes were done. Axial, sagittal, and coronal views were provided for each CBCT exposure. Furthermore, coronal sections and corrected sagittal were ready to assess all impacted/ unerupted canines for the presence of GCs, alteration in shape of GC, opening site of GC in the alveolar crest, attachment site of GC to the dental follicle, and canine eruption status. Results: The normal or delay eruption status of canines had high detection rate which were 95.9% and 100% respectively, unlike the impacted canine which had a low detection rate which was 71.2%. Only 8.9% of detected GC had alteration in shape. 54.1% of GC opened palatal or lingual to alveolar crest, 21.9% of GC was continuous with periodontal ligament (PDL) of primary canine, 20.5% of GC opened in the center of alveolar crest, and 3.5% of GC opened Buccally. 59.1% of GC was unusually attached to dental follicle, and 40.9% of GC was usually attached to dental follicle. There was a high significant difference between canine eruption status and characteristics of GC. Conclusion: The findings of this study reveal that the characteristics of GC in impacted/ unerupted canine may be a sign of an abnormal eruption condition.

Etiological Mechanisms and Genetic/Biological Modulation Related to PTH1R in Primary Failure of Tooth Eruption.

Primary failure of eruption (PFE) is a rare disorder that is characterized by the inability of a molar tooth/teeth to erupt to the occlusal plane or to normally react to orthodontic force. This condition is related to hereditary factors and has been extensively researched over many years. However, the etiological mechanisms of pathogenesis are still not fully understood. Evidence from studies on PFE cases has shown that PFE patients may carry parathyroid hormone 1 receptor (PTH1R) gene mutations, and genetic detection can be used to diagnose PFE at an early stage. PTH1R variants can lead to altered protein structure, impaired protein function, and abnormal biological activities of the cells, which may ultimately impact the behavior of teeth, as observed in PFE. Dental follicle cells play a critical role in tooth eruption and root development and are regulated by parathyroid hormone-related peptide (PTHrP)-PTH1R signaling in their differentiation and other activities. PTHrP-PTH1R signaling also regulates the activity of osteoblasts, osteoclasts and odontoclasts during tooth development and eruption. When interference occurs in the PTHrP-PTH1R signaling pathway, the normal function of dental follicles and bone remodeling are impaired. This review provides an overview of PTH1R variants and their correlation with PFE, and highlights that a disruption of PTHrP-PTH1R signaling impairs the normal process of tooth development and eruption, thus providing insight into the underlying mechanisms related to PTH1R and its role in driving PFE.