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Background: Oral and maxillofacial tissue defects resulting from factors such as trauma or infection, can significantly impact both facial function and aesthetics. Additionally, the complex anatomical structure of the face often increases the difficulty of treatment. With the advantages of controlled release, targeted delivery, and enhanced mechanical properties, injectable hydrogels have been investigated for the treatment of oral and maxillofacial diseases. In the field of regeneration, injectable hydrogels have a structure similar to the extracellular matrix (ECM) and are biocompatible, which can be used as scaffolds for tissue regeneration. Objective: This review aims to summarize the literature on the current status and limitations of injectable hydrogels in the field of oral tissue regeneration. Methods: We searched Pubmed and Web of Science databases to find and summarize the articles on the application of injectable hydrogels in tissue regeneration. Conclusions: This review focuses on the current status and limitations of injectable hydrogels in the field of tissue regeneration (periodontal tissue, dentin‐pulp complex, bone and cartilage, salivary gland regeneration, and mucosal repair). Although fully studied in animal models, there are still challenges in clinical transformation of injectable hydrogels in promoting tissue regeneration. [ABSTRACT FROM AUTHOR]

Periodontal disease is considered one of the diabetic complications with high morbidity and severity. Recent studies demonstrated the involvement of the epigenome on diabetic complications. Histone modifications change chromatin architecture and gene activation. Histone modifications have been reported to alter chromatin structure and regulate gene transcription. In this study, we investigated the impacts of H3 lysine 4 trimethylation (H3K4me3) and specific histone methyltransferases of H3K4 methylation, su(var)3-9, enhancer-of-zeste, and trithorax domain 1A (SETD1A) on periodontal tissue affected by the diabetic condition. We observed the increase in H3K4me3 and SETD1A in gingival tissue of diabetic rats compared with the normal rats. Cultured human fibroblasts (hGFs) confirmed a high glucose-induced increase in H3K4me3 and SETD1A. We further demonstrated that high glucose increased the gene expression of matrix metalloproteinase (MMP) 1 and MMP13, which were canceled by sinefungin, an SETD1A inhibitor. Our investigation suggests that diabetes triggers histone modifications in the gingival tissue, resulting in gingival inflammation. Histone modifications may play crucial roles in the development of periodontal disease in diabetes. [ABSTRACT FROM AUTHOR]

Understanding the composition and function of cells constituting tissues and organs is vital for unraveling biological processes. Single-cell analysis has allowed us to move beyond traditional methods of categorizing cell types. This innovative technology allows the transcriptional and epigenetic profiling of numerous individual cells, leading to significant insights into the development, homeostasis, and pathology of various organs and tissues in both animal models and human samples. In this review, we delve into the outcomes of major investigations using single-cell transcriptomics to decipher the cellular composition of mammalian teeth and periodontal tissues. The recent single-cell transcriptome-based studies have traced in detail the dental epithelium-ameloblast lineage and dental mesenchyme lineages in the mouse incisors and the tooth germ of both mice and humans; unraveled the microenvironment, the identity of niche cells, and cellular intricacies in the dental pulp; shed light on the molecular mechanisms orchestrating root formation; and characterized cellular dynamics of the periodontal ligament. Additionally, cellular components in dental pulps were compared between healthy and carious teeth at a single-cell level. Each section of this review contributes to a comprehensive understanding of tooth biology, offering valuable insights into developmental processes, niche cell identification, and the molecular secrets of the dental environment.

BACKGROUND: The application of orthodontic force triggers autophagy in the periodontal tissue via diverse signaling pathways, augmenting or attenuating the activity of relevant cell types such as periodontal ligament cells, osteocytes, osteoclasts, and osteoblasts, thus facilitating the process of periodontal remodeling. OBJECTIVE: To review the research progress in orthodontic force mediated autophagy in periodontal tissue and its impact on orthodontic tooth movement. METHODS: The PubMed, Web of Science, China Biology Medicine disc and CNKI were searched for literature published from 2010 to 2023 to summarize the progress in orthodontics-related autophagy. And 76 papers were finally included in the analysis and discussion. RESULTS AND CONCLUSION: Orthodontic force can trigger a series of biochemical signal changes through periodontal mechanical receptors and aseptic inflammation they cause, leading to autophagy in periodontal tissue. Subsequently, autophagy generates corresponding feedback through cascaded amplified signaling pathways such as Phosphoinositide 3-kinase/protein kinase B, Hippo, and mitogen-activated protein kinase pathways, promoting periodontal tissue remodeling and ultimately achieving tooth movement and stability. Orthodontic force-induced autophagy can differentially regulate bone resorption on the tooth pressure side and bone formation on the tension side. Related targets have good prospects in the clinical application of orthodontic treatment. Orthodontics and autophagy have complex mechanisms. However, existing research has only focused on exploring the role of autophagy in orthodontic tooth movement. Further exploration is needed to investigate the mutual regulatory effects between autophagy and orthodontic tooth movement, as well as the interactions between upstream mechanical receptors and signaling pathways involved in related pathways. [ABSTRACT FROM AUTHOR]

In this study, we established an experimental rat model to simulate orthodontic tooth movement relapse and a human periodontal ligament stem cell (PDLScs) model. Our aim was to explore the relationship between microRNA-146a (miR-146a) expression in periodontal tissue, the inflammatory factor interleukin-6 (IL-6), and orthodontic relapse subsequent to mechanical intervention. In the animal experiment, a total of 30 healthy male Wistar rats were randomly allocated to either the control group (n=6) or the model group (n=24). In the model group, the orthodontic appliance was removed 14 days after force application. Gingival crevicular fluid (GcF) and periodontal tissue samples were collected at intervals of days 0, 7, 14, and 21 following removal of the orthodontic appliance to assess alterations in miR-146a and IL-6 expressions. In the in vitro cell culture study, human premolar tooth tissue was isolated 24 hours following the addition of the transfection reagent to harvest PDLScs. Reverse transcription quantitative polymerase chain reaction was employed to evaluate the expression levels of the miRNA-146a gene, while Western blot analysis was utilized to assess the production of the IL-6 protein. As a result in comparison to the control group, the protein expression of IL-6 notably escalated to its peak value in the model-day 7 group (p<0.05). Subsequently, although experiencing a slight decline, the IL-6 expression in the modelday 14 group remained significantly elevated compared to control group (p<0.05). In the model-day 21 group, the protein expression of IL-6 approached that of the control group, with no significant difference observed (p>0.05). conversely, in relation to the control group, the gene expression of miR-146a drastically decreased to its lowest point in the model-day 7 group (p<0.05). While exhibiting a slight increase, the miR-146a expression in the model-day 14 group remained significantly diminished compared to control group (p<0.05). Following the identification of human periodontal ligament cells (hPDLcs) through immunofluorescence in the in vitro study, a subsequent experiment was conducted to specifically inhibit miR-146a expression. In comparison to the control group, the protein expression of IL-6 demonstrated a significant increase in the anti-miRNA oligodeoxyribonucleotide (AMO) group, where miR-146a expression was effectively suppressed (p<0.05). Throughout the process of orthodontic tooth movement relapse in rats, there was a notable reduction in the gene expression of miR-146a, accompanied by a significant increase in the expression of IL-6. [ABSTRACT FROM AUTHOR]

Introduction: P. gingivalis are the main bacteria that cause periodontal diseases. One of the clinical signs of periodontal disease is alveolar bone resorption. Tofu liquid waste is a typical high water-containing biomass and isoflavones. Isoflavones is a polyphenol that has an anti-inflammatory effect by reducing pro-inflammatory cytokine expression. This study aims to evaluate whether systemic administration of different tofu liquid waste doses has effects on decreasing alveolar bone resorption of the Wistar rats' periodontal tissues induced by P. gingivalis. Materials and methods:: This is true experimental research, with a randomized posttest-only group design. The groups are K (-) for the normal group, K (+) for the negative control group, and K-1, K-2, and K-3 for group induced with P.gingivalis [0.03 mL(1x 109CFU/mL)] and administrated with 6, 12, and 18 mL/kgBW tofu liquid waste respectively every day for 28 days. Results: Freeze-dried technique result showed tofu liquid waste still contains isoflavone (daidzin and glycitin). There is no difference in mean in all parameters between K(-) and K-3. K(+) has difference mean with K-1, K-2, and K-3. Correlation test showed there was a positive correlation between the dose levels of tofu liquid waste with osteoblasts and OPG, and a negative correlation between the dose levels of tofu liquid waste with lymphocytes, neutrophils, osteoclasts, RANKL, alveolar bone resorption, and periodontal ligament space. Conclusion: Tofu liquid waste administration has effects on decreasing the alveolar bone resorption of Wistar rat (Rattus norvegicus) periodontal tissues induced by P. gingivalis and 18 mL/kgBW has the highest effect. [ABSTRACT FROM AUTHOR]

Introduction: Periodontal disease is an infectious syndrome presenting inflammatory aspects. Radiographic evaluation is an essential complement to clinical assessment but has limitations such as the impossibility of assessing tissue inflammation. It seems essential to consider new exploration methods in clinical practice. Ultrasound of periodontal tissues could make it possible to visualize periodontal structures and detect periodontal diseases (periodontal pocket measurement and the presence of intra-tissue inflammation). Clinical Innovation Report: An ultrasound probe has been specially developed to explore periodontal tissues. The objective of this clinical innovation report is to present this device and expose its potential. Discussion: Various immediate advantages favor using ultrasound: no pain, no bleeding, faster execution time, and an image recording that can be replayed without having to probe the patient again. Ultrasound measurements of pocket depth appear to be as reliable and reproducible as those obtained by manual probing, as do tissue thickness measurements and the detection of intra-tissue inflammation. Conclusions: Ultrasound seems to have a broad spectrum of indications. Given the major advances offered by ultrasound imaging as a complementary aid to diagnosis, additional studies are necessary to validate these elements and clarify the potential field of application of ultrasound imaging in dentistry. [ABSTRACT FROM AUTHOR]

Proper management of orthodontic treatment in diabetic patients is essential due to the heightened risk of periodontal tissue breakdown associated with hyperglycemia. Cacao bean extracts (CBE) are known to reduce the inflammatory response and increase synthesis and angiogenesis in periodontitis. Therefore, this study aims to examine the effect of CBE on preventing periodontal tissue breakdown in diabetes with orthodontic force. A total of 25 Wistar rats were divided randomly into 5 groups, including non-diabetes, diabetes, diabetes cacao 125, 250, and 500 mg/kg BW. Diabetic rats were induced with the stratified dose of Streptozotocin, and a 30-g-force from orthodontic device was applied in all groups. Diabetes cacao group was given CBE for 7 days using a gastric probe. GCF samples were used to analyze the eNOS level through the ELISA method. NFκB, Collagen-1, and FGF-2 expression were then assessed using the immunohistochemical method, while the number of fibroblasts and blood vessels was observed using hematoxylin-eosin stained tissue. The data obtained were analyzed with one-way ANOVA and post hoc tests, with p < 0.05. CBE at a dose of 250 mg/kg BW significantly increased eNOS level, Collagen-1, and FGF-2 expression, and the number of fibroblasts and blood vessels in diabetes groups. Meanwhile, the treatment decreased NFκB expression in diabetes groups (p < 0.05). This study proved that CBE increased periodontal ligament synthesis and angiogenesis and decreased inflammatory response, thereby preventing periodontal tissue breakdown in diabetic rat models with tooth movement. [Display omitted] [ABSTRACT FROM AUTHOR]

BACKGROUND: Cell derivative is cell-derived bioactive components, including decellularized extracellular matrix, exosome, apoptotic extracellular vesicle, and conditioned medium, has the effects on immune regulation, promoting angiogenesis, bone regeneration, ligament remodeling, and is capable of promoting stem cell chemotherapy, migration, proliferation, and adhesion. Its excellent characteristics make it a promising biomaterial for application and clinical translation in the field of periodontal tissue engineering. OBJECTIVE: To review the characteristics of cell derivatives (decellularized extracellular matrix, exosome, apoptotic extracellular vesicle, and conditioned medium) and its effect and the latest progress in the field of regenerative restoration of periodontal complex tissue structures. METHODS: We searched the articles on CNKI and PubMed databases with the search terms “regeneration, periodontal tissue, tissue engineering, decellularized matrix, exosome, apoptotic extracellular vesicle, condition medium” in Chinese and English, respectively. Finally, 76 articles were included for analysis and discussion. RESULTS AND CONCLUSION: (1) Among those four cell derivatives, the decellularized extracellular matrix has the best mechanical properties and fibrous structure, serving as a biomimetic scaffold to provide physiochemical signals and participate in mechanical signaling in periodontal tissue engineering, providing supporting effect suitable for periodontal regeneration. Recently, the development of soluble decellularized extracellular matrix bioinks has enabled the fabrication of regenerative scaffolds for personalized periodontal defects. (2) Exosomes are the simplest cell derivatives that have immunomodulatory capacity, promoting cell migration and differentiation. As a carrier, they can be used to carry target molecules to regulate periodontal regeneration, promote ligament remodeling and bone regeneration, and are suitable for periodontal tissue engineering. (3) Apoptotic vesicles generated from apoptotic cells have a strong immunomodulatory effect and can recruit stem cells and macrophages, which determine the fate of stem cells through signal transduction and can enhance immunomodulation to promote periodontal regeneration. Engineered extracellular vesicle is considered to have the potential to initiate targeted internal immunomodulation. (4) The extraction of conditioned medium is simple and completely noninvasive, which provides essential nutrients and growth factors for tissue regeneration. These components are crucial for successful periodontal regeneration. Therefore, the conditioned medium is especially suitable for studying the interactions between cells in vitro and has an important role in high-throughput detection in the future. [ABSTRACT FROM AUTHOR]

Signal regulatory protein alpha (SIRPα) is mainly expressed by cells of myeloid origin. This membrane glycoprotein is shown to be involved in regulation of different inflammatory conditions, such as colitis and arthritis. However, SIRPα has not been investigated in relationship to periodontitis, an inflammatory condition affecting the tooth supporting tissues. We aim to investigate if resident cells in the periodontium express SIRPα and whether a possible expression is affected by inflammatory conditions. Primary human keratinocytes, fibroblasts, periodontal ligament cells, and osteoblasts were cultured with or without the pro-inflammatory cytokines tumor necrosis factor alpha (TNF-α) or interleukin-1-beta (IL-1β). All different periodontal cell types showed a basal mRNA expression of SIRPα. Pro-inflammatory cytokines induced a 2–3-fold significant increase in SIRPα expression in both cultured human gingival fibroblasts and osteoblasts but neither in keratinocytes nor in periodontal ligament cells. Tissue sections from human gingival tissue biopsies were histochemically stained for SIRPα. Epithelial keratinocytes and gingival fibroblasts stained positive in sections from periodontally healthy as well as in sections from periodontitis. In periodontitis sections, infiltrating leukocytes stained positive for SIRPα. We highlight our finding that oral keratinocytes, gingival fibroblasts, and periodontal ligament cells do express SIRPα, as this has not been presented before. The fact that inflammatory stimulation of gingival fibroblasts increased the expression of SIRPα, while an increased expression by gingival fibroblasts in periodontitis tissue in situ could not be detected, is indeed contradictory.

Objective To investigate the clinical characteristics, diagnosis and treatment of severe combined periodontal-endodontic lesions in a double-rooted maxillary lateral incisor with a palatal radicular groove and to provide a reference for clinical diagnosis and treatment. Methods A patient with a double-rooted left maxillary lateral incisor with a palatal radicular groove and severe combined periodontal-endodontic lesions underwent complete root canal therapy and intentional replantation, and a retrospective analysis of the management of this type of patient was performed based on the literature. Results The 3-year follow-up examination revealed no discomfort, good healing of the upper left lateral incisor, no pathological loosening, and a palatal gingival sulcus was found at a depth of approximately 1 mm. Review of the literature showed that the prognosis of the affected tooth and the choice of treatment plan were correlated with the length and depth of extension of the lingual groove toward the root, the periodontal condition and the pulpal status of the affected tooth. For minor PRGs or for affected teeth with no loss of pulpal viability, flap surgery and odontoplasty can be used to avoid endodontic treatment or retreatment. For deep or long lingual grooves that result in significant loss of periodontal tissue, endodontic treatment, odontoplasty, or closure of the grooves and guided tissue regeneration are needed. In the case of PRGs with double root formation, the affected tooth can be preserved via root canal therapy, removal of the small root and filling with apical restorative material, and intentional replantation. Conclusion In cases of severe combined periodontal-endodontic lesions due to palatal radicular grooves occurring in double-rooted maxillary lateral incisors, clinical presentation and imaging can prevent missed diagnoses, and appropriate treatment should be based on the length and depth of lingual grooves extending toward the roots, periodontal conditions, and pulpal status of the affected teeth.

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Periodontal tissue is tissue that surrounds the teeth and functions to keep the teeth in place. Various examinations can be carried out to determine the condition of the periodontal tissue, such as gingival index, bleeding on probing (BOP), and probing depth. In general, periodontal disease can be caused by 2 factors: local and systemic. One example of periodontal disease caused by systemic factors is infection with a disease or due to the influence of systemic treatment. COVID-19 is a family of coronaviridae viruses and severe acute respiratory syndrome discovered in December 2019 in Wuhan, Hubei Province, China. Transmission of this virus initially came from animals to humans (zoonosis) and then occurred on a large scale between humans. Various measures to prevent transmission and increase the severity of COVID-19 infection have been implemented, including the COVID-19 vaccination program. To determine the picture of the periodontal tissue of patients at RSGMP Soelastri Surakarta after COVID-19 vaccination. This study used research subjects, namely RSGMP Soelastri Surakarta patients who had received at least 1 dose of vaccine, and the research data were analyzed using Microsoft Excel. There were images in the periodontal tissue of patients after COVID-19 vaccination in the form of probing depth in 26 respondents and bleeding on probing in 38 respondents. Based on the results of the research and discussion above, it can be concluded that there is a picture of periodontal tissue in the form of bleeding on positive probing for bleeding in patients at RSGMP Soelastri Surakarta after 3 doses of COVID-19 vaccination with the AstraZeneca vaccine. [ABSTRACT FROM AUTHOR]

Abstract Background The surgically facilitated orthodontic strategy has been a promising strategy for orthodontic treatment recently. Therefore, the present meta-analysis was conducted to assess the available scientific evidence regarding the clinical outcomes, including the potential detrimental effects associated with these surgical procedures, with the aim of providing much more evidence-based information for clinical practice. Methods An electronic search of three databases (PubMed, Cochrane, and Embase) and a manual search of relevant articles published up to May 2023 were carried out. Clinical trials (≥ 10 subjects) that utilized surgically facilitated orthodontic strategies with clinical and/or radiographic outcomes were included. Meta-analyses and sub-group analyses were performed to analyze the standardized mean difference (SMD) or weighted mean difference (WMD), and confidence interval (CI) for the recorded variables. Results Nineteen studies published from Oct 2012 to May 2023 met the inclusion criteria. Based on the analysis outcomes, corticotomy treatment significantly decreased the alignment duration (WMD: -1.08 months; 95% CI = -1.65, -0.51 months, P = 0.0002), and accelerated the canine movement (WMD: 0.72 mm; 95% CI = 0.63, 0.81 mm, P

Background: The surgically facilitated orthodontic strategy has been a promising strategy for orthodontic treatment recently. Therefore, the present meta-analysis was conducted to assess the available scientific evidence regarding the clinical outcomes, including the potential detrimental effects associated with these surgical procedures, with the aim of providing much more evidence-based information for clinical practice. Methods: An electronic search of three databases (PubMed, Cochrane, and Embase) and a manual search of relevant articles published up to May 2023 were carried out. Clinical trials (≥ 10 subjects) that utilized surgically facilitated orthodontic strategies with clinical and/or radiographic outcomes were included. Meta-analyses and sub-group analyses were performed to analyze the standardized mean difference (SMD) or weighted mean difference (WMD), and confidence interval (CI) for the recorded variables. Results: Nineteen studies published from Oct 2012 to May 2023 met the inclusion criteria. Based on the analysis outcomes, corticotomy treatment significantly decreased the alignment duration (WMD: -1.08 months; 95% CI = -1.65, -0.51 months, P = 0.0002), and accelerated the canine movement (WMD: 0.72 mm; 95% CI = 0.63, 0.81 mm, P < 0.00001) compared to the traditional orthodontic group. The periodontally accelerated osteogenic orthodontic (PAOO) strategy markedly reduced the total treatment duration (SMD: -1.98; 95% CI = -2.59, -1.37, P < 0.00001) and increased the bone thickness (SMD:1.07; 95% CI = 0.74, 1.41, P < 0.00001) compared to traditional orthodontic treatment. Conclusion: The present study suggests that facilitated orthodontic treatment in terms of corticotomy and PAOO strategy may represent attractive and effective therapeutic strategy for orthodontic patients. [ABSTRACT FROM AUTHOR]

This article reviews the emerging field of periodontal tissue analysis in the context of forensic trauma assessment. Periodontal tissues are examined for their unique potential to improve the accuracy and scope of forensic investigations. They respond dynamically to different types of injuries, exhibiting distinct histological changes and features, thereby providing insights into the nature and timing of injuries. Although this method is promising, it also poses notable challenges, including contamination risks, post-mortem changes, and interpretation of histological results. Future implications will focus on advances in molecular analysis, integration of imaging technology, and establishment of reference databases. Standardization, quality assurance, and interdisciplinary collaboration are essential for reliable periodontal tissue analysis. In summary, periodontal tissue analysis is a dynamic and promising tool with significant implications in forensics, provided that it is used ethically and in accordance with the highest standards. This emerging field highlights the use of periodontal tissue analysis and the commitment of forensic experts needed to unravel the complexities of trauma, offering a potential path in the field of forensic science. [ABSTRACT FROM AUTHOR]

The aesthetic constancy and functional stability of periodontium largely depend on the presence of healthy mucogingival tissue. Soft tissue management is crucial to the success of periodontal surgery. Recently, synthetic substitute materials have been proposed to be used for soft tissue augmentation, but the tissue compatibility of these materials needs to be further investigated. This study aims to assess the in vitro responses of human gingival mesenchymal stromal cells (hG-MSCs) cultured on a Gelatin/Polycaprolactone prototype (GPP) and volume-stable collagen matrix (VSCM). hG-MSCs were cultured onto the GPP, VSCM, or plastic for 3, 7, and 14 days. The proliferation and/or viability were measured by cell counting kit-8 assay and resazurin-based toxicity assay. Cell morphology and adhesion were evaluated by microscopy. The gene expression of collagen type I, alpha1 (COL1A1), α-smooth muscle actin (α-SMA), fibroblast growth factor (FGF-2), vascular endothelial growth factor A (VEGF-A), transforming growth factor beta-1 (TGF-β1), focal adhesion kinase (FAK), integrin beta-1 (ITG-β1), and interleukin 8 (IL-8) was investigated by RT-qPCR. The levels of VEGF-A, TGF-β1, and IL-8 proteins in conditioned media were tested by ELISA. GPP improved both cell proliferation and viability compared to VSCM. The cells grown on GPP exhibited a distinct morphology and attachment performance. COL1A1, α-SMA, VEGF-A, FGF-2, and FAK were positively modulated in hG-MSCs on GPP at different investigation times. GPP increased the gene expression of TGF-β1 but had no effect on protein production. The level of ITG-β1 had no significant changes in cells seeded on GPP at 7 days. At 3 days, notable differences in VEGF-A, TGF-β1, and α-SMA expression levels were observed between cells seeded on GPP and those on VSCM. Meanwhile, GPP showed higher COL1A1 expression compared to VSCM after 14 days, whereas VSCM demonstrated a more significant upregulation in the production of IL-8. Taken together, our data suggest that GPP electrospun nanofibers have great potential as substitutes for soft tissue regeneration in successful periodontal surgery. [ABSTRACT FROM AUTHOR]

Silk fibroin (SF) film/porous SF-nanohydroxyapatite (nHA) double-layer composite scaffolds were fabricated by a combination of electrospinning, casting and freeze-drying. The results showed that the tensile strength and elongation of the SF film layer were significantly improved through the bridging effect of SF/(ε-caprolactone) fibers in the SF matrix. The pore size in SF-nHA porous scaffold layer was approximately 213 μm, and nHA enhanced the compressive strength of the scaffold. CCK-8 assay showed that the SF/SF-nHA scaffold not only had no obvious cytotoxicity but also significantly promoted cell proliferation. The scaffold has the potential to be used for periodontal tissue regeneration. [ABSTRACT FROM AUTHOR]

Background/purpose: The ligature-induced periodontitis model is an effective approach to induce inflammation and bone loss similar to that of human periodontitis. Previous clinical and in vitro studies have shown the involvement of lymphocytes in periodontitis, while, the local and systemic profile of immune cells associated with periodontitis in the ligature-induced periodontitis model in mice remains unclear. Materials and methods: Experimental periodontitis was constructed in mice by ligating around the maxillary second molars for 14 and 28 days, respectively. Alveolar bone loss was assessed by micro-computed tomography (micro-CT). Hematoxylin and eosin (H&E) and tartrate-resistant acid phosphatase (TRAP) staining were used to evaluate the histological changes in the periodontal tissues. B and T cells in the cervical lymph nodes, spleen, and peripheral blood were analyzed by flow cytometry. Results: The 14-day ligation effectively induced significant periodontal inflammation and alveolar bone loss in C57BL/6J mice, which were progressive and maintained for a relatively long-term period until day 28. In addition, CD3+ T cells and CD19+ B cells were the dominant population in both health and disease, and the B cell population within the cervical lymph nodes (LN) increased significantly under periodontitis condition, while, no significant differences of the T and B cell population among the spleen and peripheral blood were observed. Conclusion: The ligature-induced periodontitis mice model was established to perform a longitudinal assessment of changes in periodontal tissues morphologically and histologically, meanwhile, explore the local and systemic changes of the predominant immune-associated cells.

Introduction: Periodontal disease is an infectious syndrome presenting inflammatory aspects. Radiographic evaluation is an essential complement to clinical assessment but has limitations such as the impossibility of assessing tissue inflammation. It seems essential to consider new exploration methods in clinical practice. Ultrasound of periodontal tissues could make it possible to visualize periodontal structures and detect periodontal diseases (periodontal pocket measurement and the presence of intra-tissue inflammation). Clinical Innovation Report: An ultrasound probe has been specially developed to explore periodontal tissues. The objective of this clinical innovation report is to present this device and expose its potential. Discussion: Various immediate advantages favor using ultrasound: no pain, no bleeding, faster execution time, and an image recording that can be replayed without having to probe the patient again. Ultrasound measurements of pocket depth appear to be as reliable and reproducible as those obtained by manual probing, as do tissue thickness measurements and the detection of intra-tissue inflammation. Conclusions: Ultrasound seems to have a broad spectrum of indications. Given the major advances offered by ultrasound imaging as a complementary aid to diagnosis, additional studies are necessary to validate these elements and clarify the potential field of application of ultrasound imaging in dentistry.

BACKGROUND: Periodontal disease is a chronic inflammation of tooth supporting tissue. The destruction of these tissues leads to tooth loss. Periodontal tissue regeneration is the ultimate goal of periodontal therapy. OBJECTIVE: To review the biological characteristics of periodontal ligament stem cells and their influencing factors in promoting periodontal tissue regeneration. METHODS: Databases of PubMed, CNKI, Wanfang, ScienceDirect, and Medline were retrieved with the key words of “periodontal ligament stem cells, periodontal tissue regeneration” in English and Chinese for articles published from 2004 to 2021. The articles were screened according to the inclusion and exclusion criteria and finally 72 articles were included for review. RESULTS AND CONCLUSION: Periodontitis is a widespread disease characterized by inflammation leading to progressive damage to tooth support structures until teeth fall off. A grand goal of periodontal regeneration therapy is to repair the lost or damaged supporting tissues in periodontal tissue, including alveolar bone, periodontal ligament and cementum, and may effectively reduce the tooth loss caused by periodontitis. Stem cells for periodontal regeneration are the focus of regeneration research and it is also a potential treatment for periodontitis. Periodontal ligament stem cells may be the most suitable cells as cell sources. The in-depth study of biology also emphasizes that periodontal ligament stem cells are promising immunomodulators. However, there are a variety of factors that enhance or inhibit the role of periodontal ligament stem cells in periodontal tissue regeneration. Understanding the influence mechanism of various factors will help us to have more in-depth research in this field. [ABSTRACT FROM AUTHOR]

The ligature-induced periodontitis model is an effective approach to induce inflammation and bone loss similar to that of human periodontitis. Previous clinical and in vitro studies have shown the involvement of lymphocytes in periodontitis, while, the local and systemic profile of immune cells associated with periodontitis in the ligature-induced periodontitis model in mice remains unclear. Experimental periodontitis was constructed in mice by ligating around the maxillary second molars for 14 and 28 days, respectively. Alveolar bone loss was assessed by micro-computed tomography (micro-CT). Hematoxylin and eosin (H&E) and tartrate-resistant acid phosphatase (TRAP) staining were used to evaluate the histological changes in the periodontal tissues. B and T cells in the cervical lymph nodes, spleen, and peripheral blood were analyzed by flow cytometry. The 14-day ligation effectively induced significant periodontal inflammation and alveolar bone loss in C57BL/6J mice, which were progressive and maintained for a relatively long-term period until day 28. In addition, CD3+ T cells and CD19+ B cells were the dominant population in both health and disease, and the B cell population within the cervical lymph nodes (LN) increased significantly under periodontitis condition, while, no significant differences of the T and B cell population among the spleen and peripheral blood were observed. The ligature-induced periodontitis mice model was established to perform a longitudinal assessment of changes in periodontal tissues morphologically and histologically, meanwhile, explore the local and systemic changes of the predominant immune-associated cells. [ABSTRACT FROM AUTHOR]

Investigation on the effect of Piezo1 on periodontal tissue and periodontal ligament fibroblasts (PDLFs) under mechanical stress and the underlying mechanism. The orthodontic tooth movement rat model was established via an orthodontic spiral tension spring. PDLFs were cultured and subjected to 2.0 g/cm2 static compressive loading. Blocked the Piezo1 via Piezo1 inhibitor, GsMTx4. TUNEL staining and flow cytometry determined the apoptosis rate of periodontal tissue and PDLFs in rats. Expression of Piezo1, p‐p38 and ERK1/2 was analysed by immunofluorescence assay and western blotting. Piezo1 inhibitor GsMTx4 relieved the increased expression of Piezo1, ERK1/2 and p‐p38, and alleviated apoptosis in periodontal tissue and PDLFs under compressive loading. Piezo1 inhibition can alleviate force‐induced apoptosis and damage in rats' periodontal tissue and PDLFs, and regulate the p38/ERK1/2 signalling pathway. [ABSTRACT FROM AUTHOR]

Purpose: To use and evaluate two methods for measuring gingival thickness (GT) at mandibular incisors of orthodontic patients and compare their performance in assessing periodontal anatomy through soft tissue thickness.Materials and Methods: The sample consisted of 40 consecutive adult orthodontic patients. GT was measured just before bracket placement at both central mandibular incisors, mid-facially on the buccal aspect, 2 mm apically to the free gingival margin with two methods: clinically with an ultrasound device (USD) and radiographically with cone-beam computed tomography (CBCT).Results: CBCT measurements were consistently higher than USD measurements, with the difference ranging from 0.13 mm to 0.21 mm. No statistically significant difference was noted between the repeated CBCT measurements at the right central incisor (bias = 0.05 mm; 95% CI = -0.01, 0.11; p = 0.104). Although the respective results for the left incisor statistically indicated that the measurements were not exactly replicated, the magnitude of the point estimate was small and not clinically significant (bias = 0.06 mm; 95% CI = 0.01, 0.11; p = 0.014). Small differences between CBCT measurements made by the 2 examiners at the left central incisor (bias = 0.06 mm; 95% CI = 0.01, 0.11; p = 0.014) were detected. However, this difference was minor and also not clinically significant. The respective analysis on the right incisor showed no statistically significant difference (bias = 0.05 mm; 95% CI = -0.01, 0.11; p = 0.246).Conclusions: Based on reproducibility, CBCT imaging for gingival thickness assessment proved to be as reliable as ultrasound determination. However, CBCT consistently yielded higher values, albeit at a marginal level, than did the ultrasound device. [ABSTRACT FROM AUTHOR]

BACKGROUND: Periodontal membrane stem cells, as a kind of odontogenic mesenchymal stem cells, have osteogenic differentiation potential and can be applied to periodontal tissue regeneration and repair, while the osteogenic differentiation of periodontal membrane stem cells involves the regulation of multiple signaling pathways. OBJECTIVE: To review the factor-mediated signaling pathways associated with osteogenic differentiation of periodontal membrane stem cells and their effects on osteogenic differentiation. METHODS: In PubMed and CNKI, the search time was set from 2010 to 2022. The research progress of eight major signaling pathways associated with osteogenic differentiation of periodontal ligament stem cells since 2010 was summarized. Finally, 60 articles were included for analysis and discussion. RESULTS AND CONCLUSION: (1) Periodontal membrane stem cells, as odontogenic mesenchymal stem cells, have the characteristics of good proliferation, selfrenewal and multidirectional differentiation potential. As seed cells for periodontal tissue regeneration and restoration, periodontal membrane stem cells have broad prospects for the treatment of periodontitis. (2) At present, a large number of studies have confirmed that the potential relationship between various factors and periodontal membrane stem cell osteogenic differentiation is generated by mediating each signaling pathway. Although each signaling pathway has a certain role in promoting the osteogenic differentiation of periodontal membrane stem cells, the most studied is the MAPK signaling pathway and the Wnt signaling pathway. (3) The MAPK signaling pathway includes four pathways, which are widely present in cells and play an important role in regulating cell proliferation and differentiation. The classic Wnt/β-catenin pathway is one of the most important signaling pathways for controlling bone homeostasis, and numerous studies have confirmed its association with osteogenic differentiation of periodontal membrane stem cells. (4) At present, most of the current research has only confirmed through in vitro mineralization experiments that certain factors can activate the MAPK signaling pathway and the classic Wnt/ β-catenin pathway, improve the expression of mineralization genes, and thus promote the osteogenic differentiation of periodontal membrane stem cells, but further research is needed on how these pathways are activated and the specific mechanisms of this pathway affecting the osteogenic differentiation of periodontal membrane stem cells. (5) The activation or inhibition of various signaling pathways mediated by different research factors significantly affected the osteogenic differentiation of periodontal membrane stem cells. Understanding the signaling pathways associated with osteogenic differentiation of periodontal membrane stem cells will facilitate the application of periodontal membrane stem cells to periodontal tissue regeneration, thereby effectively reducing tooth loss due to periodontitis. [ABSTRACT FROM AUTHOR]

Abstract Orthodontic tooth movement relies on bone remodeling and periodontal tissue regeneration in response to the complicated mechanical cues on the compressive and tensive side. In general, mechanical stimulus regulates the expression of mechano-sensitive coding and non-coding genes, which in turn affects how cells are involved in bone remodeling. Growing numbers of non-coding RNAs, particularly mechano-sensitive non-coding RNA, have been verified to be essential for the regulation of osteogenesis and osteoclastogenesis and have revealed how they interact with signaling molecules to do so. This review summarizes recent findings of non-coding RNAs, including microRNAs and long non-coding RNAs, as crucial regulators of gene expression responding to mechanical stimulation, and outlines their roles in bone deposition and resorption. We focused on multiple mechano-sensitive miRNAs such as miR-21, - 29, -34, -103, -494-3p, -1246, -138-5p, -503-5p, and -3198 that play a critical role in osteogenesis function and bone resorption. The emerging roles of force-dependent regulation of lncRNAs in bone remodeling are also discussed extensively. We summarized mechano-sensitive lncRNA XIST, H19, and MALAT1 along with other lncRNAs involved in osteogenesis and osteoclastogenesis. Ultimately, we look forward to the prospects of the novel application of non-coding RNAs as potential therapeutics for tooth movement and periodontal tissue regeneration.

Periodontal tissue stem cells, which play a crucial role in maintaining the homeostasis of periodontal tissues, are found in the periodontal ligament (PDL). These cells have long been referred to as mesenchymal stem/stromal cells (MSCs), and their clinical applications have been extensively studied. However, tissue stem cells in the PDL have not been thoroughly investigated, and they may be different from MSCs. Recent advances in stem cell biology, such as genetic lineage tracing, identification of label-retaining cells, and single-cell transcriptome analysis, have made it possible to analyze tissue stem cells in the PDL in vivo. In this review, we summarize recent findings on these stem cell populations in PDL and discuss future research directions toward developing periodontal regenerative therapy.

The periodontal ligament is located between the bone (alveolar bone) and the cementum of the tooth, and it is connected by tough fibers called Sharpey's fibers. To maintain healthy teeth, the foundation supporting the teeth must be healthy. Periodontal diseases, also known as tooth loss, cause the alveolar bone to dissolve. The alveolar bone, similar to the bones in other body parts, is repeatedly resorbed by osteoclasts and renewed by osteogenic cells. This means that an old bone is constantly being resorbed and replaced by a new bone. In periodontal diseases, the alveolar bone around the teeth is absorbed, and as the disease progresses, the alveolar bone shrinks gradually. In most cases, the resorbed alveolar bone does not return to its original form even after periodontal disease is cured. Gum covers the tooth surface so that it matches the shape of the resorbed alveolar bone, exposing more of the tooth surface than before, making the teeth look longer, leaving gaps between the teeth, and in some cases causing teeth to sting. Previously, the only treatment for periodontal diseases was to stop the disease from progressing further before the teeth fell out, and restoration to the original condition was almost impossible. However, a treatment method that can help in the regeneration of the supporting tissues of the teeth destroyed by periodontal diseases and the restoration of the teeth to their original healthy state as much as possible is introduced. Recently, with improvements in implant material properties, implant therapy has become an indispensable treatment method in dentistry and an important prosthetic option. Treatment methods and techniques, which are mainly based on experience, have gradually accumulated scientific evidence, and the number of indications for treatment has increased. The development of bone augmentation methods has contributed remarkably to the expansion of indications, and this has been made possible by various advances in materials science. The induced pluripotent stem cell (iPS) cell technology for regenerating periodontal tissues, including alveolar bone, is expected to be applied in the treatment of diseases, such as tooth loss and periodontitis. This review focuses on the alveolar bone and describes clinical practice, techniques, and the latest basic research. [ABSTRACT FROM AUTHOR]

The aesthetic constancy and functional stability of periodontium largely depend on the presence of healthy mucogingival tissue. Soft tissue management is crucial to the success of periodontal surgery. Recently, synthetic substitute materials have been proposed to be used for soft tissue augmentation, but the tissue compatibility of these materials needs to be further investigated. This study aims to assess the in vitro responses of human gingival mesenchymal stromal cells (hG-MSCs) cultured on a Gelatin/Polycaprolactone prototype (GPP) and volume-stable collagen matrix (VSCM). hG-MSCs were cultured onto the GPP, VSCM, or plastic for 3, 7, and 14 days. The proliferation and/or viability were measured by cell counting kit-8 assay and resazurin-based toxicity assay. Cell morphology and adhesion were evaluated by microscopy. The gene expression of collagen type I, alpha1 (COL1A1), α-smooth muscle actin (α-SMA), fibroblast growth factor (FGF-2), vascular endothelial growth factor A (VEGF-A), transforming growth factor beta-1 (TGF-β1), focal adhesion kinase (FAK), integrin beta-1 (ITG-β1), and interleukin 8 (IL-8) was investigated by RT-qPCR. The levels of VEGF-A, TGF-β1, and IL-8 proteins in conditioned media were tested by ELISA. GPP improved both cell proliferation and viability compared to VSCM. The cells grown on GPP exhibited a distinct morphology and attachment performance. COL1A1, α-SMA, VEGF-A, FGF-2, and FAK were positively modulated in hG-MSCs on GPP at different investigation times. GPP increased the gene expression of TGF-β1 but had no effect on protein production. The level of ITG-β1 had no significant changes in cells seeded on GPP at 7 days. At 3 days, notable differences in VEGF-A, TGF-β1, and α-SMA expression levels were observed between cells seeded on GPP and those on VSCM. Meanwhile, GPP showed higher COL1A1 expression compared to VSCM after 14 days, whereas VSCM demonstrated a more significant upregulation in the production of IL-8. Taken together, our data suggest that GPP electrospun nanofibers have great potential as substitutes for soft tissue regeneration in successful periodontal surgery.

Objective To analyze changes in proteoglycan and its correlation with alveolar bone resorption in periodontitis. Methods Twelve eight-week-old C57BL/6J male mice were selected, and the periodontitis model was established by ligating the right maxillary second molar with 6-0 silk thread. The nonligated part of the left maxilla was used as the control. The mice were killed 14 days after the operation. Micro-CT was used to assess alveolar bone resorption. HE staining was used to observe the alveolar bone profile, and TRAP staining was conducted to examine the positive rate of osteoclasts. The expression of proteoglycan-related genes, such as aggrecan (ACAN), biglycan (BGN), versican (VCAN), decorin (DCN), osteoclast-related genes, such as cathepsin K (CTSK), matrix metalloprotein-9 (MMP-9), and receptor activator of nuclear factor kappa-B ligand (RANKL), and inflammation-related genes, such as interleukin-1β (IL-1β), interleukin-6 (IL-6), and tumor necrosis factor-α (TNF-α), was detected by real-time quantitative PCR. Additionally, the correlation of the expression of proteoglycans with osteoclast-related genes and inflammation-related genes was evaluated by Pearson correlation analysis. Results The resorption of alveolar bone on the periodontitis side increased. TRAP staining showed that the number of osteoclasts was substantially increased in the maxilla with periodontitis. Real-time quantitative PCR demonstrated that compared with the control side, the expression of proteoglycan-related genes, such as ACAN, BGN, and DCN, was decreased, whereas the expression of the VCAN gene was significantly increased in the periodontitis side. Meanwhile, the expression of osteoclast-related genes, such as CTSK, MMP-9, and RANKL, and inflammation-related genes, such as IL-1β, IL-6, and TNF-α, was markedly increased in the periodontitis side (P

This systematic review aims to investigate the possibilities of ultrasound imaging in the field of periodontal tissues exploration to visualize periodontal anatomical structures and to assess reliability in clinical evaluation using the PRISMA guidelines. An electronic search through the MEDLINE database was realized to identify studies that have explored ultrasonography in the field of periodontal imaging published from 2000 to March 2022. The search resulted in 245 records; after exclusions, a total of 15 papers were included in the present review. Various publications have shown the possibility of using intraoral ultrasound for a precise exploration of intraoral tissues and to perform measurements of periodontal structures. Studies argue that ultrasounds open the prospect of a complete paradigm shift on the diagnosis and follow-up of periodontal disease. However, there is currently no clinical device dedicated to periodontal ultrasound. This field is still under-studied, and studies are needed to explore the large field of applications from periodontal assessment to treatment reassessment, including surgery. Researchers should focus their efforts to develop special intraoral ultrasound device and explore the possibilities of clinical periodontal applications. [ABSTRACT FROM AUTHOR]

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Human periodontal ligament cells (hPDLCs) are known as ideal seed cells for the regeneration of periodontal tissues. Several factors (i.e., vitamin D3, luteolin, and 6-bromoindirubin-3′-oxime) have been shown to promote osteogenic differentiation of hPDLCs. In this study, we aim to investigate the effect of vitamin A on cell proliferation, migration, and osteogenic differentiation of hPDLCs. hPDLCs were cultured in osteogenic induction medium supplemented with different concentrations of vitamin A. Cell proliferation and migration assays were conducted after 24, 48, and 72 h of incubation, whereas osteogenic differentiation and osteogenesis-related gene expression were assessed after 21 d only. Our results demonstrated that 1-µM vitamin A stimulation exerted the most potent promotion effect on cell proliferation, migration, and osteogenic differentiation of hPDLCs. It also induced significant upregulation of osteogenic differentiation–related genes and mitochondrial complexes II and IV in hPDLCs. Vitamin A may serve as a promising potential candidate for periodontal tissue regeneration. [ABSTRACT FROM AUTHOR]

Orthodontic tooth movement relies on bone remodeling and periodontal tissue regeneration in response to the complicated mechanical cues on the compressive and tensive side. In general, mechanical stimulus regulates the expression of mechano-sensitive coding and non-coding genes, which in turn affects how cells are involved in bone remodeling. Growing numbers of non-coding RNAs, particularly mechano-sensitive non-coding RNA, have been verified to be essential for the regulation of osteogenesis and osteoclastogenesis and have revealed how they interact with signaling molecules to do so. This review summarizes recent findings of non-coding RNAs, including microRNAs and long non-coding RNAs, as crucial regulators of gene expression responding to mechanical stimulation, and outlines their roles in bone deposition and resorption. We focused on multiple mechano-sensitive miRNAs such as miR-21, - 29, -34, -103, -494-3p, -1246, -138-5p, -503-5p, and -3198 that play a critical role in osteogenesis function and bone resorption. The emerging roles of force-dependent regulation of lncRNAs in bone remodeling are also discussed extensively. We summarized mechano-sensitive lncRNA XIST, H19, and MALAT1 along with other lncRNAs involved in osteogenesis and osteoclastogenesis. Ultimately, we look forward to the prospects of the novel application of non-coding RNAs as potential therapeutics for tooth movement and periodontal tissue regeneration. [ABSTRACT FROM AUTHOR]

BACKGROUND: Periodontitis is one of main diseases that cause destruction of alveolar bone and tooth loss in adults. To improve the regeneration effect, regulating bone homeostasis in periodontal tissue through modifying controllable properties of materials can effectively improve the effect of alveolar bone regeneration, which provides a popular development direction of periodontal biomaterials. OBJECTIVE: To summarize the current research status of local bone homeostasis imbalance in periodontitis and periodontal biomaterial modification strategies based on the concept of regulating bone homeostasis, and to discuss the prospects and challenges of current strategies in periodontal regeneration. METHODS: The articles were searched on Web of Science, PubMed, CNKI, and Wanfang databases. The Chinese and English key words were “bone, periodontal tissue, homeostasis, biomaterials, regeneration”. The publication time was limited from January 2000 to December 2020. The articles that were associated with the review content were selected according to the topic. Sixty-one articles were included for the final analysis after excluding the articles that were not related to the content of the article. RESULTS AND CONCLUSION: (1) Oral microflora, its products and inflammation destroy the dynamic balance of osteogenesis and osteoclast metabolism in the periodontal tissue. (2) Physical and chemical properties of biomaterials may affect the dynamic balance of bone homeostasis of periodontal tissue. Therefore, the local bone homeostasis can be adjusted by changing the physical and chemical properties of the material. The main methods include: modifying the physical properties of the material, transmitting biological activity, adjusting inflammatory response, and inhibiting osteoclast production. (3) The concept of regulating bone homeostasis is applied to the development of periodontal biomaterials, which improves the osteogenic effect of periodontal biomaterials, and promotes the development of periodontal tissue engineering materials and clinical periodontal regeneration. [ABSTRACT FROM AUTHOR]

Periodontal tissue stem cells, which play a crucial role in maintaining the homeostasis of periodontal tissues, are found in the periodontal ligament (PDL). These cells have long been referred to as mesenchymal stem/stromal cells (MSCs), and their clinical applications have been extensively studied. However, tissue stem cells in the PDL have not been thoroughly investigated, and they may be different from MSCs. Recent advances in stem cell biology, such as genetic lineage tracing, identification of label-retaining cells, and single-cell transcriptome analysis, have made it possible to analyze tissue stem cells in the PDL in vivo. In this review, we summarize recent findings on these stem cell populations in PDL and discuss future research directions toward developing periodontal regenerative therapy. [ABSTRACT FROM AUTHOR]

BACKGROUND: Periodontal disease is a chronic inflammation of tooth supporting tissue. The destruction of these tissues leads to tooth loss. Periodontal tissue regeneration is the ultimate goal of periodontal therapy.OBJECTIVE: To review the biological characteristics of periodontal ligament stem cells and their influencing factors in promoting periodontal tissue regeneration.METHODS: Databases of PubMed, CNKI, Wanfang, ScienceDirect, and Medline were retrieved with the key words of “periodontal ligament stem cells, periodontal tissue regeneration” in English and Chinese for articles published from 2004 to 2021. The articles were screened according to the inclusion and exclusion criteria and finally 72 articles were included for review. RESULTS AND CONCLUSION: Periodontitis is a widespread disease characterized by inflammation leading to progressive damage to tooth support structures until teeth fall off. A grand goal of periodontal regeneration therapy is to repair the lost or damaged supporting tissues in periodontal tissue, including alveolar bone, periodontal ligament and cementum, and may effectively reduce the tooth loss caused by periodontitis. Stem cells for periodontal regeneration are the focus of regeneration research and it is also a potential treatment for periodontitis. Periodontal ligament stem cells may be the most suitable cells as cell sources. The in-depth study of biology also emphasizes that periodontal ligament stem cells are promising immunomodulators. However, there are a variety of factors that enhance or inhibit the role of periodontal ligament stem cells in periodontal tissue regeneration. Understanding the influence mechanism of various factors will help us to have more in-depth research in this field. [ABSTRACT FROM AUTHOR]

This research aimed to evaluate Mask R-CNN and U-Net convolutional neural network models for pixel-level classification in order to perform the automatic segmentation of bi-dimensional images of US dental arches, identifying anatomical elements required for periodontal diagnosis. A secondary aim was to evaluate the efficiency of a correction method of the ground truth masks segmented by an operator, for improving the quality of the datasets used for training the neural network models, by 3D ultrasound reconstructions of the examined periodontal tissue. Methods: Ultrasound periodontal investigations were performed for 52 teeth of 11 patients using a 3D ultrasound scanner prototype. The original ultrasound images were segmented by a low experienced operator using region growing-based segmentation algorithms. Three-dimensional ultrasound reconstructions were used for the quality check and correction of the segmentation. Mask R-CNN and U-NET were trained and used for prediction of periodontal tissue's elements identification. Results: The average Intersection over Union ranged between 10% for the periodontal pocket and 75.6% for gingiva. Even though the original dataset contained 3417 images from 11 patients, and the corrected dataset only 2135 images from 5 patients, the prediction's accuracy is significantly better for the models trained with the corrected dataset. Conclusions: The proposed quality check and correction method by evaluating in the 3D space the operator's ground truth segmentation had a positive impact on the quality of the datasets demonstrated through higher IoU after retraining the models using the corrected dataset. [ABSTRACT FROM AUTHOR]

Periodontal tissue supports teeth in the alveolar bone socket via fibrous attachment of the periodontal ligament (PDL). The PDL contains periodontal fibroblasts and stem/progenitor cells, collectively known as PDL cells (PDLCs), on top of osteoblasts and cementoblasts on the surface of alveolar bone and cementum, respectively. However, the characteristics and lineage hierarchy of each cell type remain poorly defined. This study identified periodontal ligament associated protein-1 (Plap-1) as a PDL-specific extracellular matrix protein. We generated knock-in mice expressing CreERT2 and GFP specifically in Plap-1-positive PDLCs. Genetic lineage tracing confirmed the longstanding hypothesis that PDLCs differentiate into osteoblasts and cementoblasts. A PDL single-cell atlas defined cementoblasts and osteoblasts as Plap-1-Ibsp+Sparcl1+ and Plap-1-Ibsp+Col11a2+, respectively. Other populations, such as Nes+ mural cells, S100B+ Schwann cells, and other non-stromal cells, were also identified. RNA velocity analysis suggested that a Plap-1highLy6a+ cell population was the source of PDLCs. Lineage tracing of Plap-1+ PDLCs during periodontal injury showed periodontal tissue regeneration by PDLCs. Our study defines diverse cell populations in PDL and clarifies the role of PDLCs in periodontal tissue homeostasis and repair. [ABSTRACT FROM AUTHOR]

Background: Periodontal disease is a chronic inflammatory disease caused by periodontal bacteria. Recently, periodontal phototherapy, treatment using various types of lasers, has attracted attention. Purpose: This in vitro study was aimed to compare and evaluate the effect of lasers with different wave lengths on proliferation and differentiation of periodontal ligament stem cells to stimulate periodontal reattachment. Materials and Methods: A randomized and controlled study design was used to evaluate the effect of low-level laser therapy (LLLT) delivered at different doses over dental fibroblast cell culture in high glucose medium. Results: Comparison between MTT Assay results for the normal group under wavelength 635 and 980 under laser energy 0.5, 1, and 2 and after 24, 48, 72, and 96 hours. All results were significant except the results after 24 hours in MTT 635 assay, Conclusion: The response of cell viability was significantly higher for non-diabetic cases in comparison to diabetic ones for both 635 & 980 nm lasers with different doses and at different time points. Our results also suggested that the cell viability was dosed dependent. [ABSTRACT FROM AUTHOR]

Multiple systems and associated factors have been described in the literature to assess the prognosis of teeth with periodontal disease. Nowadays there is a tendency among clinicians to consider implants as the best solution after tooth extraction, in cases of teeth with a questionable prognosis. However, the value of the natural tooth must be considered, as the proprioception of the periodontal ligament is preserved, and it adapts to stress during functional loads. We first review the literature focusing on analyzing the factors that should guide decision-making to maintain or extract a tooth with a compromised periodontium. Then, we propose a schematic diagram of prognostic indicators to reflect the main factors to consider and the survival rate that each one represents when preserving or extracting a tooth. [ABSTRACT FROM AUTHOR]

BACKGROUND: As a kind of dental mesenchymal stem cells, dental follicle stem cells have considerable application prospect and clinical transformation value in stem cell therapy and tissue engineering because of their excellent characteristics. OBJECTIVE: To review the basic characteristics of dental follicle stem cells and their latest progress in the field of regeneration and repair of tooth and periodontal complex tissue structure. METHODS: The key words were “dental follicle stem cell, regeneration, tooth, bone, periodontal tissue, tissue engineering, review” in Chinese and English. PubMed, Science direct, Medline, CBM, CNKI, and other databases were retrieved in articles published from 2010 to 2021. Finally, 61 articles were included for analysis and discussion. RESULTS AND CONCLUSION: As dental mesenchymal stem cells, dental follicle stem cells have great application value in the field of oral regenerative medicine, and they have the characteristics of rich sources, multi-directional differentiation, and low immunogenicity. At present, dental follicle stem cells are actively used in the regeneration of periodontal tissue, tissue engineering biological root reconstruction and alveolar bone repair. Their therapeutic potential in other tissue injuries and immune system diseases has been continuously explored in recent years. However, before more in-depth clinical application, how to better regulate the functional mechanism of transplanted dental follicle stem cells and control the immune system response, in order to further optimize the construction methods of teeth and periodontal tissue, is worthy of in-depth research and discussion. [ABSTRACT FROM AUTHOR]

Abstract Background The biocompatibility of NeoMTA Plus® (Avlon BioMed Inc., Bradenton, Fl) as a furcal perforation repair material is not fully understood. This study compares the biocompatibility of Mineral Trioxide Aggregate (MTA Angelus) and NeoMTA Plus® as delayed furcation perforation repair materials. Methods Pulpotomy and root canal obturation were performed in 72 premolars in six mongrel dogs and then a standardized furcal perforation was performed. The coronal access was left open for three weeks. After curetting, cleaning and drying of the perforations, these teeth were divided into three equal groups (N = 24 teeth/ 2 dogs each) according to the material used for perforation repair; group I: NeoMTA Plus®, group II: MTA Angelus and group III: no material (positive control). The coronal access cavities were sealed with a filling material. The inflammatory cell count and qualitative pathology (presence of calcific bridge, configuration of fibrous tissue formed, examination of tissue surrounding the furcation area, histology of intraradicular bone and the inflammatory nature of tissues) were carried out after one week (subgroup A, N = 8 teeth), one month (subgroup B, N = 8 teeth) and three months (subgroup C, N = 8 teeth). The inflammatory cell count was expressed as mean ± SD and statistically analyzed. P-value 0.05). In contrast to group II, there was no significant differences in inflammatory cell count between the subgroups in groups I and III (P > 0.05). NeoMTA Plus® exhibited better qualitative pathological features than MTA Angelus after one week and nearly similar features after one month and three months of repair. Conclusion NeoMTA Plus® has a better early biocompatibility than MTA Angelus after one week of delayed furcation perforation repair and a similar late biocompatibility after one month and three months.

In the process of orthodontic treatment, the balance between the modeling of alveolar bone and the mechanical stress exerted by the appliance is key to the effective movement of orthodontic teeth. Alveolar bone modeling involves many regulatory factors, and microRNAs (miRNAs), as posttranscriptional regulatory factors, play an important role in the occurrence of bone modeling. As an important member of the miRNA family, miRNA-21 promotes the differentiation of periodontal ligament stem cells into osteoblasts and plays an important role in maintaining bone balance and preventing bone resorption as a regulator of osteoclast formation and a promoter of osteoclast differentiation. A literature review showed that miRNA-21 can regulate osteoclast function and promote bone resorption through programmed cell death 4 (PDCD4), phosphate and tension homology deleted on chromosome ten (PTEN), receptor activator of nuclear factor-κB ligand (RANKL) and osteoprotegerin (OPG). MiRNA-21 is highly sensitive to external mechanical stress in the process of orthodontic tooth movement. After orthodontic force is applied, miRNA-21 can promote osteoclast formation and accelerate orthodontic movement; through targeted regulation of periodontal ligament associated protein-1 (PLAP-1), it can regulate periodontal ligament remodeling in the late stage of tooth movement and improve the potential of tooth movement. In addition, miRNA-21 mediates orthodontic tooth movement (OTM) and alveolar bone remodeling in the periodontal inflammatory microenvironment. miRNA-21 can upregulate the expression of hypoxia-inducible factor-1α (HIF-1α) in periodontal ligament stem cells in a hypoxic environment. It can promote the expression of osteogenic markers, such as osteopontin (OPN), osteocalcin (OCN), alkaline phosphatase (ALP) and runt-related transcription factor 2 (Runx2), and promote osteogenic differentiation during orthodontic tooth movement.

The periodontal ligament is located between the bone (alveolar bone) and the cementum of the tooth, and it is connected by tough fibers called Sharpey’s fibers. To maintain healthy teeth, the foundation supporting the teeth must be healthy. Periodontal diseases, also known as tooth loss, cause the alveolar bone to dissolve. The alveolar bone, similar to the bones in other body parts, is repeatedly resorbed by osteoclasts and renewed by osteogenic cells. This means that an old bone is constantly being resorbed and replaced by a new bone. In periodontal diseases, the alveolar bone around the teeth is absorbed, and as the disease progresses, the alveolar bone shrinks gradually. In most cases, the resorbed alveolar bone does not return to its original form even after periodontal disease is cured. Gum covers the tooth surface so that it matches the shape of the resorbed alveolar bone, exposing more of the tooth surface than before, making the teeth look longer, leaving gaps between the teeth, and in some cases causing teeth to sting. Previously, the only treatment for periodontal diseases was to stop the disease from progressing further before the teeth fell out, and restoration to the original condition was almost impossible. However, a treatment method that can help in the regeneration of the supporting tissues of the teeth destroyed by periodontal diseases and the restoration of the teeth to their original healthy state as much as possible is introduced. Recently, with improvements in implant material properties, implant therapy has become an indispensable treatment method in dentistry and an important prosthetic option. Treatment methods and techniques, which are mainly based on experience, have gradually accumulated scientific evidence, and the number of indications for treatment has increased. The development of bone augmentation methods has contributed remarkably to the expansion of indications, and this has been made possible by various advances in materials science. The induced pluripotent stem cell (iPS) cell technology for regenerating periodontal tissues, including alveolar bone, is expected to be applied in the treatment of diseases, such as tooth loss and periodontitis. This review focuses on the alveolar bone and describes clinical practice, techniques, and the latest basic research.

• Acidification is induced in the gingival sulcus of mechanically forced tooth. • Buffering the gingival acidity ameliorates orthodontic mechanical allodynia. • ASIC3 is involved in the mechanical allodynia induced by orthodontic force. • Tooth movement causes ASIC3 phosphorylation in the periodontal tissue. Tooth movements associated with orthodontic treatment often cause tooth pain. However, the detailed mechanism remains unclear. Here, we examined the involvement of periodontal acidification caused by tooth movement in mechanical tooth pain hypersensitivity. Elastics were inserted between the first and second molars to move the teeth in Sprague-Dawley rats. Mechanical head-withdrawal reflex threshold to first molar stimulation and the pH of the gingival sulcus around the tooth were measured. The expression of acid-sensing ion channel 3 (ASIC3) in trigeminal ganglion neurons and phosphorylation of ASIC3 in the periodontal tissue were analyzed. The mechanical head-withdrawal reflex threshold to first molar stimulation and pH in the gingival sulcus decreased on day 1 after the elastic insertion. These decreases recovered to the sham level by buffering periodontal acidification. Periodontal inhibition of ASIC3 channel activity reversed the decreased mechanical head-withdrawal reflex threshold to first molar stimulation. On day 1 after elastic insertion, the tooth movement did not change the number of ASIC3 immunoreactive trigeminal ganglion neurons innervating the periodontal tissue but increased phosphorylated-ASIC3 levels in the periodontal tissue. Periodontal acidification induced by tooth movement causes phosphorylation of ASIC3, resulting in mechanical pain hypersensitivity in mechanically forced tooth. [ABSTRACT FROM AUTHOR]

To investigate the aesthetic efficacy and effect of fiber post, composite resin and zirconia porcelain crown on periodontal tissue in the treatment of wedge-shaped defects of posterior teeth after root canal treatment. Methods: 103 cases of wedge-shaped defects of posterior teeth after root canal treatment in our hospital from January 2018 to March 2019 were selected as the research objects, were divided into control group (n=52, affected teeth 62) and the research group (n=51, affected teeth 63) according to different restoration materials. The patients in the control group were treated with metal post core and metal porcelain crown repair, while the patients in the research group were treated with fiber post, composite resin and zirconia porcelain crown repair. The repair success rate and repair effect of the two groups 1 year after repaired were compared. The gingival index, plaque index, depth of periodontal probe, gingival crevicular fluid amount and alkaline phosphatase (ALP) and aspartate aminotransferase (AST) in gingival crevicular fluid of gingival crevicular fluid of the two groups before repaired and 1year after repaired were compared. Results: The repair success rate of research group was higher than that of control group(P<0.05). The surface smooth rate, edge tight rate, good fixation rate and color match rate of restoration of the research group were significantly higher than those of the control group (P<0.05). The gingival index, plaque index, depth of periodontal probe of the two groups were significantly lower than before treatment (P<0.05), the gingival crevicular fluid amount and ALP, AST of gingival crevicular fluid of the two groups were significantly lower than before treatment (P<0.05), and the gingival index, plaque index, depth of periodontal probe of the research group were lower than those of control group (P<0.05), but there were no significantly differences of the gingival crevicular fluid amount and ALP, AST of gingival crevicular fluid of the two groups aftertreatment (P>0.05).Conclusion: Fiber post, composite resin and zirconia porcelain crown on periodontal tissue in the treatment of wedge-shaped defects of posterior teeth after root canal treatment has high success rate, with good aesthetic effect, and little influence on periodontal tissue. [ABSTRACT FROM AUTHOR]

Periodontal disease is one of the most common diagnoses in small animal veterinary medicine. This infectious disease of the periodontium is characterized by the inflammation and destruction of the supporting structures of teeth, including periodontal ligament, cementum, and alveolar bone. Traditional periodontal repair techniques make use of open flap debridement, application of graft materials, and membranes to prevent epithelial downgrowth and formation of a long junctional epithelium, which inhibits regeneration and true healing. These techniques have variable efficacy and are made more challenging in veterinary patients due to the cost of treatment for clients, need for anesthesia for surgery and reevaluation, and difficulty in performing necessary diligent home care to maintain oral health. Tissue engineering focuses on methods to regenerate the periodontal apparatus and not simply to repair the tissue, with the possibility of restoring normal physiological functions and health to a previously diseased site. This paper examines tissue engineering applications in periodontal disease by discussing experimental studies that focus on dogs and other animal species where it could potentially be applied in veterinary medicine. The main areas of focus of tissue engineering are discussed, including scaffolds, signaling molecules, stem cells, and gene therapy. To date, although outcomes can still be unpredictable, tissue engineering has been proven to successfully regenerate lost periodontal tissues and this new possibility for treating veterinary patients is discussed. [ABSTRACT FROM AUTHOR]

Background. Determining what dentists know and believe about periodontal tissue properties is important to establish prevention practices. The present study aimed to investigate the knowledge, attitude, and practice of general dental practitioners about the properties of periodontal tissue around retainable teeth in Birjand, Northeast Iran. Methods. The knowledge, practice, and attitude of 91 dentists about periodontal tissue properties around retainable teeth were assessed by a validated researcher-made questionnaire. Results. The results showed that the mean score of dentists’ attitude, knowledge, and practice were 70.7, 88.2, and 77, respectively. The mean score of the attitude of male dentists was higher than females significantly (P = 0.014). Conclusion. It is highly recommended that continuing courses should be held to improve their knowledge.