Endodontic microsurgery(EMS)can handle challenging endodontic cases effectively.However,the com-plexity and postoperative outcome of EMS are closely related to multiple factors such as the patient's general condition,the affected tooth,and the surrounding anatomical structures.This article draws on international and domestic medical standards,including the American Society of Anesthesiologists,the American Association of Endodontists,the World Health Organization,and the expert consensus on the assessment of root canal treatment difficulty in China.Based on the basic principles,procedures,and anatomical data of EMS,combined with long-term clinical experience,clinical epidemio-logy,and evidence-based medicine,this article analyzes the difficult and complex factors of EMS cases.This work aims to provide references for treatment decisions,doctor-patient communication,application and promotion,clinical tea-ching,and hierarchical referral in EMS.

The subjective interpretation of periapical radiographs for dental caries and apical periodontitis remains a diagnostic challenge, often failing to detect subtle lesions. To address this, we developed an interpretable deep learning framework that leverages a novel cross-modal self-supervised pretraining strategy on 21 587 unlabeled panoramic single-tooth images, followed by fine-tuning on 6 457 expert-annotated periapical radiographs. Our model employed a dual-head Vision Transformer architecture to simultaneously yet separately classify caries and periapical lesion (PL). This approach significantly enhanced performance, elevating the F1-score from 0.81 to 0.91, with sensitivity rising from 0.76 to 0.90 and specificity from 0.88 to 0.93 compared to training from scratch. The dual-head design also surpassed a single-head, four-class classifier in disease-level accuracy, with notable improvements in complex cases such as teeth with both conditions. Attention rollout heatmaps confirmed that predictions were based on anatomically plausible regions, validating the model's clinical interpretability. Our work demonstrated that cross-modal pretraining combined with a task-specific architecture creates a highly accurate and trustworthy tool for tooth-level diagnosis and quality assurance.

Background: Clinically, apical barrier procedure can be adopted to create an immediate artificial barrier for tooth with an open apex. Given that the quality of the barrier is crucial, the apical barrier procedure is known for its high technical sensitivity, posing significant learning challenges for dental students. Therefore, a new dental teaching model not only effectively enhances the future clinical skills of dental students but also benefits a wider range of patients. Objective: A new dental model for simulating apical barrier procedure in vitro, is helpful for dental students to practice apical barrier procedure. This study aims to design, assess, and evaluate the feasibility of a three-dimensional (3D) printed apical barrier model for pre-clinical dental education. Methods: A novel 3D-printed apical barrier model was developed, consisting of a tooth model and a matching blind box. Total 200 3D-printed apical barrier models were used to train dental students, and fifty fifth-year dental students participated in this voluntary hands-on course. Each student performed apical barrier procedures on four 3D-printed models. The outcome of the first model served as the representative result for the "direct barrier group", whereas the outcome of the fourth model represented the result of the "post-training barrier group". The quality of the apical barrier procedure was assessed through X-ray examination, and a questionnaire was used to evaluate the 3D-printed model's benefits, with scores ranging from 1 (strongly agree) to 5 (strongly disagree). Results: The overall rating for the 3D-printed model was 2.0 +/- 0.6. The model was noted for its high degree of realism, ease of use, and practical applicability. Post-training assessments showed significant improvements in the density of apical barrier fillings (P< 0.05), reduction in underfilling rates (P< 0.05), and decrease in overfilling distances (P< 0.05). Students overwhelmingly agreed that the model was beneficial for training in apical barrier procedures (1.06 +/- 0.24), helped identify their shortcomings (1.62 +/- 0.53), and improved their operational skills (1.90 +/- 0.51). Conclusions: Both the questionnaire feedback and the quality of the fillings confirmed the feasibility and efficacy of the 3D-printed apical barrier model for dental education. The students had the possibility to learn the correct apical barrier procedure on printed dental models.

This study aimed to compare the clinical efficacy of a novel apical barrier technique (N-ABT) and a traditional apical barrier technique (T-ABT). A randomized controlled clinical trial was conducted. Forty-seven patients with 50 teeth meeting the inclusion criteria of large root canals and incompletely developed apical foramina were enrolled. Teeth were randomly assigned to either the N-ABT or T-ABT group in a 1:1 ratio and were followed for 24 months. N-ABT employed 3D printing technology to design personalized pluggers and to calculate the precise volume of barrier material, while T-ABT used a standard commercial plugger without volume control. Randomization was performed using a computer-generated sequence, and the study was conducted in a single-blind manner. A total of 45 teeth completed the 24-month follow-up (22 in the N-ABT group and 23 in the T-ABT group), with no significant adverse events reported. All cases were considered clinically successful, defined by the absence of symptoms and a reduction in apical radiolucency. Success was further classified as healed (complete disappearance of apical radiolucency) or healing (reduction in apical radiolucency). At the 12-month follow-up, the N-ABT group showed a slightly higher healed rate (22.7 www.chictr.org.cn (Identifier: ChiCTR2200058635;Trial title: Personalized Root Canal Barrier Technique Using 3D Printing Technology).

Cutaneous wound healing remains a common health problem. Metal-organic frameworks (MOFs) have emerged as an advanced therapeutic platform for promoted wound healing. However, there is a lack of MOF particles possessing excellent stability, biocompatibility, and reactive oxygen species (ROS) scavenging ability for tight orchestration of wound healing. Herein, we synthetize therapeutic MOF particles named PgC3Zn and employ them as skin sprays for wound repair. At the inflammatory stage, the pH- and ROS-responsive Zn2+ release of PgC3Zn alleviates oxidative stress and exerts antibacterial and anti-inflammatory efficacy. During the proliferation stage, PgC3Zn promote the migration and proliferation of fibroblasts, the re-epithelialization of keratinocytes, and the angiogenesis of endothelial cells. During the remodeling stage, PgC3Zn effectively facilitate the wound closure and collagen deposition. Moreover, multiple endogenous growth factors have been identified to contribute to the wound healing process. Importantly, PgC3Zn exhibit excellent biocompatibility and remarkably accelerate the healing process in both acute and infected rat full-thickness skin wound models in vivo. Consistently, transcriptomic data illustrate the multi-stage and multi-functional regulation effects of PgC3Zn in promoting wound healing. This study proposes versatile and biocompatible PgC3Zn MOF particles with potentials for enhancing the management of acute and infected skin wounds.

Perfluorooctane sulfonic acid (PFOS), a persistent organic pollutant, poses significant environmental risks due to its widespread contamination of agricultural systems. However, its phytotoxic mechanisms on Arabidopsis root growth and regeneration remain incompletely understood. In this study, we systematically investigated PFOS phytotoxicity and revealed its multimodal inhibitory effects on root growth, stem cell maintenance and regeneration. Our results demonstrated that PFOS exposure induced concentration-dependent reductions in primary root length, meristem size, and meristematic cortex cell number. Crucially, we observed downregulation of PLT2 expression in the root stem cell niche, whereas the auxin transporters PIN1/PIN2 and other key stem cell regulators (SHR, SCR, PLT1) remained largely unaltered under PFOS stress. This suppression of PLT2 correlated with both meristem dysfunction and impaired regeneration capacity. Furthermore, PFOS triggered oxidative stress and promoted root cell death. Taken together, these findings provide crucial insights into the mechanisms of PFOS phytotoxicity. The discovery of PLT2-mediated effects offers new perspectives for understanding how pollutants affect plant development and regeneration.

Aim or purpose: Human dental pulp stem cells (hDPSCs) are widely recognized as a promising stem cell-based therapy for peripheral nerve injuries due to their ability to secrete neurotrophic factors (NTs). However, the influence of physical factors in matrix on hDPSC-derived NT secretion and its role in bone defects remains unclear. This study aims to investigate the influence of stiffness on NT secretion by hDPSCs and to determine whether this regulation following their transplantation in periapical mandible defects contributes to bone regeneration dependent on bone mesenchymal stem cells (BMSCs). Materials and methods: First, we used RNA sequencing to screen the functional enrichment of differentially expressed genes in hDPSCs cultured on substrates with varying stiffness. We then assessed NT expression and secretion after neurogenic induction. Subsequently, we inhibited NTs in hDPSCs using siRNA, and the conditioned medium from these cells was used to induce osteogenic differentiation of BMSC. Additionally, we transplanted different stiffness gels mixed with hDPSCs into mouse molar periapical bone defects to analyze mandible regeneration in association with varying matrix stiffness. Results: Our results highlight two points: 1) hDPSCs cultured on softer matrix tended to express and secrete more NTs, particularly following neurogenic induction; 2) The mixture of neurogenic-induced hDPSCs with soft gels enhanced healing of periapical bone defects compared to stiff gels, while NT knockdown diminished this effect. Conclusions: In conclusion, a soft matrix promotes NT secretion by transplanted hDPSCs, thereby contributing to periapical mandible regeneration . This study provides new strategies for the application of dental pulp stem cells in mandible regenerative medicine.

Cranial bone defects remain a major clinical challenge, increasing patients' life burdens. Tricarboxylic acid (TCA) cycle metabolites play crucial roles in facilitating bone tissue regeneration. However, the development of TCA cycle metabolite-modified biomimetic grafts for skull bone regeneration still needs to be improved. The mechanism underlying the release of TCA cycle metabolites from biomaterials in regulating immune responses and mesenchymal stem cell (MSC) fate (migration and differentiation) remains unknown. Herein, this work constructs biomimetic hydrogels composed of gelatin and chitosan networks covalently cross-linked by genipin (CGG hydrogels). A series of TCA cycle metabolite-coordinated CGG hydrogels with strong mechanical and antiswelling performances are subsequently developed. Remarkably, the citrate (Na3Cit, Cit)-coordinated CGG hydrogels (CGG-Cit hydrogels) with the highest mechanical modulus and strength significantly promote skull bone regeneration in rat and murine cranial defects. Mechanistically, using a transgenic mouse model, bulk RNA sequencing, and single-cell RNA sequencing, this work demonstrates that CGG-Cit hydrogels promote Gli1+ MSC migration via neutrophil-secreted oncostatin M. Results also indicate that citrate improves osteogenesis via enhanced histone H3K9 acetylation on osteogenic master genes. Taken together, the immune microenvironment- and MSC fate-regulated CGG-Cit hydrogels represent a highly efficient and facile approach toward skull bone tissue regeneration with great potential for bench-to-bedside translation.

Hippo-independent YAP dysfunction has been demonstrated to cause chronological aging of stromal cells by impairing the integrity of nuclear envelope (NE). In parallel with this report, we uncover that YAP activity also controls another type of cellular senescence, the replicative senescence in in vitro expansion of mesenchymal stromal cells (MSCs), but this event is Hippo phosphorylation-dependent, and there exist another NE integrity-independent downstream mechanisms of YAP. Specifically, Hippo phosphorylation causes reduced nuclear/active YAP and then decreases the level of YAP protein in the proceeding of replicative senescence. YAP/TEAD governs RRM2 expression to release replicative toxicity (RT) via licensing G1/S transition. Besides, YAP controls the core transcriptomics of RT to delay the onset of genome instability and enhances DNA damage response/repair. Hippo-off mutations of YAP (YAPS127A/S381A ) satisfactorily release RT via maintaining cell cycle and reducing genome instability, finally rejuvenating MSCs and restoring their regenerative capabilities without risks of tumorigenesis.

The role of regulated cell death in organ development, particularly the impact of non-apoptotic cell death, remains largely uncharted. Ferroptosis, a non-apoptotic cell death pathway known for its iron dependence and lethal lipid peroxidation, is currently being rigorously investigated for its pathological functions. The balance between ferroptotic stress (iron and iron-dependent lipid peroxidation) and ferroptosis supervising pathways (anti-lipid peroxidation systems) serves as the key mechanism regulating the activation of ferroptosis. Compared with other forms of regulated necrotic cell death, ferroptosis is critically related to the metabolism of lipid and iron which are also important in organ development. In our study, we examined the role of ferroptosis in organogenesis using an ex vivo tooth germ culture model, investigating the presence and impact of ferroptotic stress on tooth germ development. Our findings revealed that ferroptotic stress increased during tooth development, while the expression of glutathione peroxidase 4 (Gpx4), a crucial anti-lipid peroxidation enzyme, also escalated in dental epithelium/mesenchyme cells. The inhibition of ferroptosis was found to partially rescue erastin-impaired tooth morphogenesis. Our results suggest that while ferroptotic stress is present during tooth organogenesis, its effects are efficaciously controlled by the subsequent upregulation of Gpx4. Notably, an overabundance of ferroptotic stress, as induced by erastin, suppresses tooth morphogenesis.

Dynamic chromatin accessibility regulates stem cell fate determination and tissue homeostasis via controlling gene expression. As a histone-modifying enzyme that predominantly mediates methylation of lysine 27 in histone H3 (H3K27me1/2/3), Polycomb repressive complex 2 (PRC2) plays the canonical role in targeting developmental regulators during stem cell differentiation and transformation. Embryonic ectoderm development (EED), the core scaffold subunit of PRC2 and as an H3K27me3-recognizing protein, has been broadly implicated with PRC2 stabilization and allosterically stimulated PRC2. Accumulating evidences from experimental data indicate that EED-associating epigenetic modifications are indispensable for stem cell maintenance and differentiation into specific cell lineages. In this review, we discuss the most updated advances to summarize the structural architecture of EED and its contributions and underlying mechanisms to mediating lineage differentiation of different stem cells during epigenetic modification to expand our understanding of PRC2.

对于内源性因素引起的牙齿色泽改变,牙齿内漂白可以达到基本无损的治疗效果,但仍然伴有多种并发症如牙颈部外吸收、颜色复发、影响牙本质粘接、影响牙齿组织结构及性能、软组织损伤等.本文根据牙齿内漂白术后可能出现的问题,阐述了各种并发症可能的发生机制,进行有针对性地处理及预防,强调了牙齿内漂白过程中和治疗后的注意事项,旨在提示临床医生在操作过程中及治疗后随访时需要注意的细节,以减少牙齿内漂白后并发症的发生,降低其危害.

Increased intracranial pressure after traumatic brain injury (TBI) is an urgent problem in clinical practice. A pliable hydrogel is preferred for cranioplasty applications after TBI since it can protect brain tissue and promote bone healing. Nevertheless, biohydrogels for cranial bone regeneration still face challenges of poor mechanical properties, large swelling ratios, and low osteogenesis activity. Herein, inspired by Hofmeister effects, biopolymer hydrogels composed of protein and polysaccharides were treated with a Hofmeister series including a series of monovalent and divalent anions. Our results reveal that the divalent anion-cross-linked biohydrogels exhibit stronger mechanical properties and lower swelling ratios compared with monovalent-anion treated gels. Intriguingly, the divalent HPO42- anion induced biohybrid hydrogels with excellent mechanical behaviors (3.7 ± 0.58 MPa, 484 ± 76.7 kPa, and 148.3 ± 6.85 kJ/m3), anti-swelling capability (16.7%), and gradual degradation ability, significantly stimulating osteogenic differentiation and in vivo cranial bone regeneration. Overall, this study may provide new insights into the design of biomimetic hydrogels for treating cranial bone defects after TBI.

骨髓间充质干细胞(BMSCs)的骨组织工程技术是目前治疗骨缺损的前沿方法.目前BMSCs的研究多聚焦于躯干骨(如髂骨)和附肢骨(如长骨)来源的BMSCs,而大量研究显示颅颌面骨(如颌骨)来源的BMSCs相较于其他部位来源的BM-SCs在表型和功能上存在差异.本文对颌骨与其他部位来源BMSCs的比较研究作一综述,从而推测颌骨来源的BMSCs具有更强的应用潜能,更适合作为骨组织工程(尤其是颅颌面骨缺损修复)的种子细胞.

牙髓再生基础研究需要动物体内模型进行实验验证,笔者在Pubmed网站对"pulp regeneration"、"stem cell"、"animal model"等关键词进行检索,根据文献内容将基于细胞移植的牙髓再生动物体内模型分为异位再生模型、半原位再生模型和原位再生模型,并对其优缺点与临床意义进行综述.根据文献综述结果,目前研究支持:异位再生模型使用最多,操作简单,但不能模拟临床情况;半原位再生模型是异位再生模型的创新,可以简单营造出更为真实的再生环境;原位再生模型可以真实模拟临床相关流程及操作,但因为操作难度大、周期长,少有使用.以上三种动物模型在实验不同阶段有不同的应用价值:异位再生模型适合实验初期测试外植入体安全性和是否具备再生能力;半原位再生模型适合对有再生能力的外植入体进行深入的再生效果评价;原位再生模型适合在临床研究之前对有明确再生能力的外植入体进行符合临床应用的再生效果和实用性评价.

The repair of large-size cranial bone defects caused by traumatic brain injury (TBI) remains a substantial clinical challenge. On one hand, traditional bone implants with intrinsic brittle and poor recovery features hinder their immediate implantation for cranioplasty applications. On the other hand, using exogenous growth factors to enhance the osteo-bioactivity of bone implants often leads to efficacy, safety, and cost concerns. Thus far, the authors develop a growth factor-free pliable hydrogel with multiple functions for mediating endogenous growth factor production and stem cell functions in cranioplasty. The pliable hydrogels are based on GelMA networks, in which the mechanical properties and protein affinity were strengthened by the crosslinked poly (ethylene glycol) disuccinimidyl succinate (PEG-(SS)2), while the antioxidant capability and osteoinductivity were remarkedly enhanced through the decoration of magnesium-seamed C-propylpyrogallol[4]arene cages (PgC3Mg). In vitro and in vivo results confirmed that the versatile hydrogel with excellent biocompatibility and biodegradability can improve osteogenic differentiation and cranial bone regeneration by facilitating growth factor production, endogenous cell recruitment and angiogenesis. These findings indicate that the versatile hydrogels represent a potential avenue for developing growth factor-free pliable scaffolds in cranioplasty after TBI.

人牙髓干细胞是再生医学中的主要细胞来源之一,具有多向分化潜能,已经被应用于治疗多种疾病,包括Ⅰ型糖尿病、神经系统疾病等.为满足临床需求,牙髓干细胞需进行体外扩增.常规的牙髓干细胞体外扩增方法需要运用添加胎牛血清的培养基,但近些年来由于胎牛血清存在伦理和安全两方面的问题,推荐使用无血清培养方法.本文对无血清培养基培养人牙髓干细胞的组成及方法,及其培育出的细胞的特性和其他相关应用进行综述.

The repair of large bone defects is an urgent problem in the clinic. Note that the disruption of redox homeostasis around bone defect sites might hinder the new bone reconstruction. The rational design of hydrogels for bone regeneration still faces the challenges of insufficient antioxidant capability and weak osteogenesis performance. Here, motivated by the versatile therapeutic functions of metal-organic cages, magnesium-seamed C-propylpyrogallol[4]arene (PgC3Mg) functionalized biodegradable and porous gelatin methacrylate (GelMA) hydrogels are constructed. The novel metal-organic cages endow hydrogels with highly bioactive characteristics and strong reactive oxygen species (ROS)-scavenging ability owing to the simultaneous release of bioactive Mg2+ ions and antioxidant phenolic hydroxyl-rich moieties. The in vitro results reveal that the PgC3Mg modified biocompatible hydrogels show higher expression of osteo-related genes and significantly eliminate the intracellular ROS levels of bone marrow-derived mesenchymal stem cells (BMSCs) against oxidative damage. Meanwhile, the bioactive and ROS scavenging hydrogels can accelerate bone regeneration in large cranial defects. Overall, this study may provide new insights into the designing of regenerative bone grafts with simultaneously enhanced osteogenic and antioxidant capabilities.

Abstract Polyvinyl alcohol (PVA) is a synthetic polymer that has been extensively studied for fabricating porous membranes via electrospinning for diverse biomedical applications. However, the poor mechanical properties of electrostatically spun PVA nanofiber membranes severely limit their application in the biomedical field. Therefore, porous, tough hybrid PVA‐based fibrous membranes were prepared by introducing poly (1,8‐octanediol citrate) (POC) into PVA fibrous membranes followed by sodium citrate treatment. The tensile modulus, fracture strength, and fracture toughness of the sodium citrate‐treated PVA/POC (CPP) membranes achieve 119.81 ± 5.32 MPa, 10.34 ± 1.57 MPa and 401.51 ± 11.67 MJ m−2, respectively, which were ∼60, ∼10, and ∼4 times higher than those achieved by the pristine PVA membrane. Moreover, the novel CPP membranes exhibited suitable biodegradation ratios and high cell/issue affinities, suggesting their potential biomedical applications in soft or hard tissue repair. This strategy, which provides porous structures, high mechanical properties and excellent biocompatibility, demonstrates a facile but effective approach for the development of advanced biomaterials.

Although biomimetic hydrogels play an essential role in guiding bone remodeling, reconstructing large bone defects is still a significant challenge since bioinspired gels often lack osteoconductive capacity, robust mechanical properties and suitable antioxidant ability for bone regeneration. To address these challenges, we first engineered molecular design of hydrogels (gelatin/polyethylene glycol diacrylate/2-(dimethylamino)ethyl methacrylate, GPEGD), where their mechanical properties were significantly enhanced via introducing trace amounts of additives (0.5 wt%). The novel hybrid hydrogels show high compressive strength (>700 kPa), stiff modulus (>170 kPa) and strong ROS-scavenging ability. Furthermore, to endow the GPEGD hydrogels excellent osteoinductions, novel biocompatible, antioxidant and BMP-2 loaded polydopamine/heparin nanoparticles (BPDAH) were developed for functionalization of the GPEGD gels (BPDAH-GPEGD). In vitro results indicate that the antioxidant BPDAH-GPEGD is able to deplete elevated ROS levels to protect cells viability against ROS damage. More importantly, the BPDAH-GPEGD hydrogels have good biocompatibility and promote the osteo differentiation of preosteoblasts and bone regenerations. At 4 and 8 weeks after implantation of the hydrogels in a mandibular bone defect, Micro-computed tomography and histology results show greater bone volume and enhancements in the quality and rate of bone regeneration in the BPDAH-GPEGD hydrogels. Thus, the multiscale design of stiffening and ROS scavenging hydrogels could serve as a promising material for bone regeneration applications.