Tooth morphogenesis is orchestrated by a complex interplay of signaling pathways and transcription factors that control cell proliferation,apoptosis,and differentiation,with the Wnt/β-catenin signaling pathway playin...Tooth morphogenesis is orchestrated by a complex interplay of signaling pathways and transcription factors that control cell proliferation,apoptosis,and differentiation,with the Wnt/β-catenin signaling pathway playing a pivotal role.However,the comprehensive regulatory mechanisms of Wnt/β-catenin signaling remain largely unclear.Smad7,a key antagonist of the TGF-βsuperfamily,is essential for maintaining tissue homeostasis and ensuring proper cellular function.Our previous study has demonstrated that Smad7 knockout in mice leads to impaired proliferative property of tooth germ cells,resulting in small molars.Here,we identified SMAD7 expression in human dental papilla and dental pulp,colocalized with β-CATENIN and cell proliferationrelated proteins.RNA sequencing analysis revealed a significant reduction in Wnt signaling activity in Smad7-deficient mouse tooth germs.Using lentivirus transfection,we established SMAD7-knockdown human dental papilla stem cells,which manifested remarkably blunt proliferation rate,along with diminished Wnt signaling activity.In vivo transplantation investigations further revealed the indispensable role of SMAD7 in dentin formation.Mechanistically,we revealed that β-CATENIN interacts with P-SMAD2/3 and SMAD7 through co-immunoprecipitation and yeast two-hybrid assays.Inhibition of TGF-β pathway or disruption of SMAD7/β-CATENIN transcription factor complex formation potently impacted Wnt/β-catenin activities,indicating both direct and indirect regulatory mechanisms.These findings highlight the critical role of SMAD7 in the proliferation and diffe rentiation of human dental stem cells,which could contribute to dental tissue regeneration and engineering.展开更多
In order to eliminate the meshing interference between the flexspline and circular spline after the taper deformation of the flexspline,the radial deformation difference method,major and minor axis fitting method,and ...In order to eliminate the meshing interference between the flexspline and circular spline after the taper deformation of the flexspline,the radial deformation difference method,major and minor axis fitting method,and ellipse fitting method are used to modify the tooth thickness of the flexspline and analyze the performance indexes such as the assembly stress,transmission error,and fatigue life.Firstly,the conjugate tooth profile is solved based on the quadruple-circular-arc tooth profile and modified kinematic method.Then,based on the finite element radial deformation of the flexspline,the principle and characteristics of three modification methods are analyzed,and the modification amount of each section of the flexspline tooth is calculated.Finally,the influence of the three modification methods on the performance of the harmonic drive is compared.The results show that the radial deformation difference method can initially determine the modification amount.The minimum static assembly stress is 406.22 MPa by the major and minor axis fitting method.The ellipse fitting method has the best dynamic performance,small transmission error fluctuation,a peak-to-peak value of 3.060",and a maximum fatigue life of 10^(7.558)cycles.展开更多
Tooth developmental anomalies are a group of disorders caused by unfavorable factors affecting the tooth development process,resulting in abnormalities in tooth number,structure,and morphology.These anomalies typicall...Tooth developmental anomalies are a group of disorders caused by unfavorable factors affecting the tooth development process,resulting in abnormalities in tooth number,structure,and morphology.These anomalies typically manifest during childhood,impairing dental function,maxillofacial development,and facial aesthetics,while also potentially impacting overall physical and mental health.The complex etiology and diverse clinical phenotypes of these anomalies pose significant challenges for prevention,early diagnosis,and treatment.As they usually emerge early in life,long-term management and multidisciplinary collaboration in dental care are essential.However,there is currently a lack of systematic clinical guidelines for the diagnosis and treatment of these conditions,adding to the difficulties in clinical practice.In response to this need,this expert consensus summarizes the classifications,etiology,typical clinical manifestations,and diagnostic criteria of tooth developmental anomalies based on current clinical evidence.It also provides prevention strategies and stage-specific clinical management recommendations to guide clinicians in diagnosis and treatment,promoting early intervention and standardized care for these anomalies.展开更多
Accurate and early evaluation of dental physiological characteristics is essential for effective disease detection and management.Polarization-sensitive optical coherence tomography(PS-OCT)is a noninvasive high-resolu...Accurate and early evaluation of dental physiological characteristics is essential for effective disease detection and management.Polarization-sensitive optical coherence tomography(PS-OCT)is a noninvasive high-resolution imaging technique that can obtain tooth structure and physiological features through intensity,retardation and degree of polarization uniformity(DOPU)images.In this study,we use the information provided by the PS-OCT system,especially the retardation information,to assess the physiological characteristics of teeth.In addition,we introduce a novel parameter—the rate of change of the retardation value(R)—to evaluate the magnitude of birefringence of enamel,which serves as an indicator of enamel health and mineralization.The results demonstrate that PS-OCT not only provides structural detail comparable to microcomputed tomography(microCT),but also yields additional physiological characteristics insights through polarization-based contrast.These findings highlight the strong potential of PS-OCT for early diagnosis,functional evaluation and personalized monitoring in dental care.展开更多
This study develops a contact performance-driven method for skiving face gear drives using a single cutter,eliminating the traditional need for separate cutters to reduce production costs and time.First,the mathematic...This study develops a contact performance-driven method for skiving face gear drives using a single cutter,eliminating the traditional need for separate cutters to reduce production costs and time.First,the mathematical models of the tooth flanks for the face gear drives are established based on the gear skiving processes.Then,load tooth contact analysis(LTCA)model is established to calculate the contact performance data.Next,a two-stage optimization model is employed to determine the optimal parameters of the cutting edge with improved contact performances.The effectiveness of this method is validated through simulations and rolling tests.Compared with the traditional method,the proposed method can machine both the face gear and its mating pinion with a single cutter.Simulation results show that the proposed method avoids tooth surface edge contact,with the maximum tooth surface contact stress reduced by 31.7%,the contact ratio decreases by 21.5%,and the transmission error increases by 22.3%.Rolling tests verify the consistency of tooth surface contact patterns between simulations and experiments.The proposed method provides a reference for the cutting edge design of skiving cutters for face gear pairs.展开更多
Nerve regeneration following traumatic peripheral nerve injuries and neuropathies is a complex process modulated by diverse factors and intricate molecular mechanisms.Past studies have focused on factors that stimulat...Nerve regeneration following traumatic peripheral nerve injuries and neuropathies is a complex process modulated by diverse factors and intricate molecular mechanisms.Past studies have focused on factors that stimulate axonal outgrowth and myelin regeneration.However,recent studies have highlighted the pivotal role of autophagy in peripheral nerve regeneration,particularly in the context of traumatic injuries.Consequently,autophagy-targeting modulation has emerged as a promising therapeutic approach to enhancing peripheral nerve regeneration.Our current understanding suggests that activating autophagy facilitates the rapid clearance of damaged axons and myelin sheaths,thereby enhancing neuronal survival and mitigating injury-induced oxidative stress and inflammation.These actions collectively contribute to creating a favorable microenvironment for structural and functional nerve regeneration.A range of autophagyinducing drugs and interventions have demonstrated beneficial effects in alleviating peripheral neuropathy and promoting nerve regeneration in preclinical models of traumatic peripheral nerve injuries.This review delves into the regulation of autophagy in cell types involved in peripheral nerve regeneration,summarizing the potential drugs and interventions that can be harnessed to promote this process.We hope that our review will offer novel insights and perspectives on the exploitation of autophagy pathways in the treatment of peripheral nerve injuries and neuropathies.展开更多
Instrument separation is a critical complication during root canal therapy,impacting treatment success and long-term tooth preservation.The etiology of instrument separation is multifactorial,involving the intricate a...Instrument separation is a critical complication during root canal therapy,impacting treatment success and long-term tooth preservation.The etiology of instrument separation is multifactorial,involving the intricate anatomy of the root canal system,instrument-related factors,and instrumentation techniques.Instrument separation can hinder thorough cleaning,shaping,and obturation of the root canal,posing challenges to successful treatment outcomes.Although retrieval of separated instrument is often feasible,it carries risks including perforation,excessive removal of tooth structure and root fractures.Effective management of separated instruments requires a comprehensive understanding of the contributing factors,meticulous preoperative assessment,and precise evaluation of the retrieval difficulty.The application of appropriate retrieval techniques is essential to minimize complications and optimize clinical outcomes.The current manuscript provides a framework for understanding the causes,risk factors,and clinical management principles of instrument separation.By integrating effective strategies,endodontists can enhance decision-making,improve endodontic treatment success and ensure the preservation of natural dentition.展开更多
Corticotomy is a clinical procedure to accelerate orthodontic tooth movement characterized by the regional acceleratory phenomenon(RAP).Despite its therapeutic effects,the surgical risk and unclear mechanism hamper th...Corticotomy is a clinical procedure to accelerate orthodontic tooth movement characterized by the regional acceleratory phenomenon(RAP).Despite its therapeutic effects,the surgical risk and unclear mechanism hamper the clinical application.Numerous evidences support macrophages as the key immune cells during bone remodeling.Our study discovered that the monocyte-derived macrophages primarily exhibited a pro-inflammatory phenotype that dominated bone remodeling in corticotomy by CX3CR1CreERT2;R26GFP lineage tracing system.Fluorescence staining,flow cytometry analysis,and western blot determined the significantly enhanced expression of binding immunoglobulin protein(BiP)and emphasized the activation of sensor activating transcription factor 6(ATF6)in macrophages.Then,we verified that macrophage specific ATF6 deletion(ATF6f/f;CX3CR1CreERT2 mice)decreased the proportion of pro-inflammatory macrophages and therefore blocked the acceleration effect of corticotomy.In contrast,macrophage ATF6 overexpression exaggerated the acceleration of orthodontic tooth movement.In vitro experiments also proved that higher proportion of pro-inflammatory macrophages was positively correlated with higher expression of ATF6.At the mechanism level,RNA-seq and CUT&Tag analysis demonstrated that ATF6 modulated the macrophage-orchestrated inflammation through interacting with Tnfαpromotor and augmenting its transcription.Additionally,molecular docking simulation and dual-luciferase reporter system indicated the possible binding sites outside of the traditional endoplasmic reticulum-stress response element(ERSE).Taken together,ATF6 may aggravate orthodontic bone remodeling by promoting Tnfαtranscription in macrophages,suggesting that ATF6 may represent a promising therapeutic target for non-invasive accelerated orthodontics.展开更多
Tissue interactions play a crucial role in tooth development.Notably,extracellular vesicle-mediated interactions between the mandible and tooth germ are considered essential.Here,we revealed that mandible extracellula...Tissue interactions play a crucial role in tooth development.Notably,extracellular vesicle-mediated interactions between the mandible and tooth germ are considered essential.Here,we revealed that mandible extracellular vesicles could modulate the proliferation and differentiation of dental mesenchymal cells by regulating the histone demethylase KDM2B.Further investigation showed that mandible derived extracellular vesicles could deliver miR-206 to KDM2B,thereby regulating tooth development.An animal study demonstrated that the miR-206/KDM2B pathway affected tooth morphogenesis and mineralization after eight weeks of subcutaneous transplantation in nude mice.In conclusion,this study suggested that the mandible played a critical role in tooth morphogenesis and mineralization,which could be a potential therapeutic target for abnormal tooth development and an alternative model for tooth regeneration.展开更多
Dental mesenchymal stem cells(DMSCs)are pivotal for tooth development and periodontal tissue health and play an important role in tissue engineering and regenerative medicine because of their multidirectional differen...Dental mesenchymal stem cells(DMSCs)are pivotal for tooth development and periodontal tissue health and play an important role in tissue engineering and regenerative medicine because of their multidirectional differentiation potential and self-renewal ability.The cellular microenvironment regulates the fate of stem cells and can be modified using various optimization techniques.These methods can influence the cellular microenvironment,activate disparate signaling pathways,and induce different biological effects.“Epigenetic regulation”refers to the process of influencing gene expression and regulating cell fate without altering DNA sequences,such as histone methylation.Histone methylation modifications regulate pivotal transcription factors governing DMSCs differentiation into osteo-/odontogenic lineages.The most important sites of histone methylation in tooth organization were found to be H3K4,H3K9,and H3K27.Histone methylation affects gene expression and regulates stem cell differentiation by maintaining a delicate balance between major trimethylation sites,generating distinct chromatin structures associated with specific downstream transcriptional states.Several crucial signaling pathways associated with osteogenic differentiation are susceptible to modulation via histone methylation modifications.A deeper understanding of the regulatory mechanisms governing histone methylation modifications in osteo-/odontogenic differentiation and immune-inflammatory responses of DMSCs will facilitate further investigation of the epigenetic regulation of histone methylation in DMSC-mediated tissue regeneration and inflammation.Here is a concise overview of the pivotal functions of epigenetic histone methylation at H3K4,H3K9,and H3K27 in the regulation of osteo-/odontogenic differentiation and renewal of DMSCs in both non-inflammatory and inflammatory microenvironments.This review summarizes the current research on these processes in the context of tissue regeneration and therapeutic interventions.展开更多
Spiral bevel gears are critical transmission components,and are widely used in the aerospace field.This paper proposes a new multi-DOF envelope forming process for fabricating spiral bevel gears.Firstly,the multi-DOF ...Spiral bevel gears are critical transmission components,and are widely used in the aerospace field.This paper proposes a new multi-DOF envelope forming process for fabricating spiral bevel gears.Firstly,the multi-DOF envelope forming principle of spiral bevel gears is proposed.Secondly,the design methods for the envelope tool geometry and movement are proposed based on the envelope geometry and movement relationships.Thirdly,the metal flow and tooth filling laws are revealed through 3D FE simulation of the multi-DOF envelope forming process of a typical spiral bevel gear.Fourthly,a new method for separating the envelope tool and the formed spiral bevel gear with back taper tooth is proposed to avoid their interference.Finally,experiments on multi-DOF envelope forming of this typical spiral bevel gear are conducted using new heavy load multi-DOF envelope forming equipment.The simulation and experimental results show the feasibility of the proposed multi-DOF envelope forming process for fabricating spiral bevel gears with back taper tooth and the corresponding process design methods.展开更多
The regulatory processes in developmental biology research are significantly influenced by long non-coding RNAs(lncRNAs).However,the dynamics of lncRNA expression during human tooth development remain poorly understoo...The regulatory processes in developmental biology research are significantly influenced by long non-coding RNAs(lncRNAs).However,the dynamics of lncRNA expression during human tooth development remain poorly understood.In this research,we examined the lncRNAs present in the dental epithelium(DE)and dental mesenchyme(DM)at the late bud,cap,and early bell stages of human fetal tooth development through bulk RNA sequencing.Developmental regulators co-expressed with neighboring lncRNAs were significantly enriched in odontogenesis.Specific lncRNAs expressed in the DE and DM,such as PANCR,MIR205HG,DLX6-AS1,and DNM3OS,were identified through a combination of bulk RNA sequencing and single-cell analysis.Further subcluster analysis revealed lncRNAs specifically expressed in important regions of the tooth germ,such as the inner enamel epithelium and coronal dental papilla(CDP).Functionally,we demonstrated that CDP-specific DLX6-AS1 enhanced odontoblastic differentiation in human tooth germ mesenchymal cells and dental pulp stem cells.These findings suggest that lncRNAs could serve as valuable cell markers for tooth development and potential therapeutic targets for tooth regeneration.展开更多
The contact characteristics of the rough tooth surface during the meshing process are significantly affected by the lubrication state.The coupling effect of tooth surface roughness and lubrication on meshing character...The contact characteristics of the rough tooth surface during the meshing process are significantly affected by the lubrication state.The coupling effect of tooth surface roughness and lubrication on meshing characteristics of planetary gear is studied.An improved three-dimensional(3 D)anisotropic tooth surface roughness fractal model is proposed based on the experimental parameters.Considering asperity contact and elastohydrodynamic lubrication(EHL),the contact load and flexibility deformation of the tooth surface are derived,and the deformation compatibility equation of the 3 D loaded tooth contact analysis(3 D-LTCA)method is improved.The asperity of the tooth surface changes the system from EHL to mixed lubrication and reduces the stiffness of the oil film.Compared with the sun planet gear,the asperity has a greater effect on the meshing characteristics of the ring-planet gear.Compared with the proposed method,the comprehensive stiffness obtained by the traditional calculation method considering the lubrication effect is smaller,especially for the ring-planet gear.Compared with roughness,speed and viscosity,the meshing characteristics of planetary gears are most sensitive to torque.展开更多
Tooth cracks may occur in spiral bevel gear transmission system of the aerospace equipment.In this study,an accurate and efficient loaded tooth contact analysis(LTCA)model is developed to predict the contact behavior ...Tooth cracks may occur in spiral bevel gear transmission system of the aerospace equipment.In this study,an accurate and efficient loaded tooth contact analysis(LTCA)model is developed to predict the contact behavior and time-varying meshing stiffness(TVMS)of spiral bevel gear pair with cracked tooth.The tooth is sliced,and the contact points on slices are computed using roll angle surfaces.Considering the geometric complexity of crack surface,a set of procedures is formulated to generate spatial crack and determine crack parameters for contact points.According to the positional relationship between contact point and crack path,each sliced tooth is modeled as a non-uniform cantilever beam with varying reduced effective load-bearing tooth thickness.Then the compliance model of the cracked tooth is established to perform contact analysis,along with TVMS calculations utilizing three different models.By employing spiral bevel gear pairs with distinct types of cracks as examples,the accuracy and efficiency of the developed approach are validated via comparative analyses with finite element analysis(FEA)outcomes.Furthermore,the investigation on effects of cracks shows that tooth cracks can induce alterations in meshing performance of both entire gear pair and individual tooth pairs,including not only cracked tooth pair but also adjacent non-cracked tooth pairs.Hence,the proposed model can serve as a useful tool for analyzing the variations in contact behavior and meshing stiffness of spiral bevel gears due to different cracks.展开更多
The repair of the periodontal membrane is essential for the successful management of periodontal disease and dental trauma.Emdogain®(EMD)is widely used in periodontal therapy due to its ability to promote repair....The repair of the periodontal membrane is essential for the successful management of periodontal disease and dental trauma.Emdogain®(EMD)is widely used in periodontal therapy due to its ability to promote repair.Despite substantial research,the cellular and molecular mechanisms underlying EMD’s effects,particularly at the single-cell resolution,remain incompletely understood.This study established a delayed tooth replantation model in rats to investigate these aspects.Tooth loss rate and degree of loosening were evaluated at 4 and 8 weeks.Micro-CT,HE staining,TRAP staining,and immunofluorescence staining were evaluated to assess EMD’s efficacy.Single-cell sequencing analyses generated single-cell maps that explored enrichment pathways,cell communication,and potential repair mechanisms.Findings indicated that EMD could reduce the rate of tooth loss,promote periodontal membrane repair,and reduce root and bone resorption.Single-cell analysis revealed that EMD promotes the importance of Vtn+fibroblasts,enhancing matrix and tissue regeneration functions.Additionally,EMD stimulated osteogenic pathways,reduced osteoclastic activity,and promoted angiogenesis-related pathways,particularly bone-related H-type vessel expression in endothelial cells.Gene modules associated with angiogenesis,osteogenesis,and odontoblast differentiation were identified,suggesting EMD might facilitate osteogenesis and odontoblast differentiation by upregulating endothelium-related genes.Immune cell analysis indicated that EMD did not elicit a significant immune response.Cell communication analysis suggested that EMD fostered pro-regenerative networks driven by interactions between mesenchymal stem cells,fibroblasts,and endothelial cells.In conclusion,EMD proves to be an effective root surface therapy agent that supports the restoration of delayed replantation teeth.展开更多
Intentional tooth replantation(ITR)is an advanced treatment modality and the procedure of last resort for preserving teeth with inaccessible endodontic or resorptive lesions.ITR is defined as the deliberate extraction...Intentional tooth replantation(ITR)is an advanced treatment modality and the procedure of last resort for preserving teeth with inaccessible endodontic or resorptive lesions.ITR is defined as the deliberate extraction of a tooth;evaluation of the root surface,endodontic manipulation,and repair;and placement of the tooth back into its original socket.Case reports,case series,cohort studies,and randomized controlled trials have demonstrated the efficacy of ITR in the retention of natural teeth that are untreatable or difficult to manage with root canal treatment or endodontic microsurgery.However,variations in clinical protocols for ITR exist due to the empirical nature of the original protocols and rapid advancements in the field of oral biology and dental materials.This heterogeneity in protocols may cause confusion among dental practitioners;therefore,guidelines and considerations for ITR should be explicated.This expert consensus discusses the biological foundation of ITR,the available clinical protocols and current status of ITR in treating teeth with refractory apical periodontitis or anatomical aberration,and the main complications of this treatment,aiming to refine the clinical management of ITR in accordance with the progress of basic research and clinical studies;the findings suggest that ITR may become a more consistent evidence-based option in dental treatment.展开更多
Background: Tooth loss results in impaired mastication, which in turn, makes it difficult to chew hard food, consequently leading to deteriorate dietary habits and to develop hypertension. The purpose of this study wa...Background: Tooth loss results in impaired mastication, which in turn, makes it difficult to chew hard food, consequently leading to deteriorate dietary habits and to develop hypertension. The purpose of this study was to examine the effect of tooth loss on blood pressure among Congolese population. Methods: A cross-sectional study was conducted from October 2019 until December 2023 among Congolese population aged at least 30 years reporting to the living in DR Congo. All participants were enrolled from Dental Clinic located in the DR Congo. To be eligible to participate in the study, were the willing to participate and having signed informed consent;had a missing tooth;had carried out blood pressure measurement (hypertension/normotensive). The exclusion criteria were determined: being less than 30 years old, being pregnant for women considering the risk of existing gestational hypertension, obesity, excessive alcohol consumption, smoking, and diabetes. Hypertension was defined as the mean of three measurements of systolic blood pressure (SBP) (140 mmHg or higher), diastolic blood pressure (DBP) (90 mm or higher) or physician diagnosed hypertension confirmed from medical records. We determined the number of tooth loss from oral examination. A multivariable logistic regression model was used to investigate the effect of tooth loss on blood pressure. Results: In all, 25,396 participants were enrolled among Congolese population for this study. After oral examination, 13,421 were excluded for no tooth loss and 11,975 participants were selected. The average number of tooth loss among study population was 11.06. Among the participants with hypertension had lost an average of 11 teeth, significantly higher than those without hypertension (6.09) (p = 0.001). After adjusting for covariates (socio-demographic characteristics), tooth loss (>10) was significantly associated with hypertension, with OR = 1.32 (95% CI 1.073 - 2.38). Conclusion: Tooth loss maybe associated with severe hypertension among Congolese population adults. Prevention of tooth loss is very important to the overall health of this population.展开更多
BACKGROUND This study analyzed the dental follicle and alveolar bone of two patients with tooth eruption disorders,aiming to provide some reference for exploring the etiology and selecting treatment plans of this dise...BACKGROUND This study analyzed the dental follicle and alveolar bone of two patients with tooth eruption disorders,aiming to provide some reference for exploring the etiology and selecting treatment plans of this disease from the perspective of the influence of extracellular matrix on osteoclasts differentiation in dental follicle.CASE SUMMARY Collect dental follicle and alveolar bone tissue from one patient with single tooth eruption disorder and one patient with full permanent tooth eruption disorder,respectively.Simultaneously collect the dental follicle and alveolar bone tissue of obstructed teeth that need to be extracted due to orthodontic treatment as the control group.Hematoxylin and eosin(HE)staining was used to observe the morphology of dental follicle cells.Immunohistochemical staining was used to observe the expression of periostin,receptor activator of nuclear factor kappa B ligand(RANKL),and osteoprotegerin(OPG)protein in dental follicle and alveolar bone tissue.And observe the eruption of teeth after removing resistance from the crown of the permanent tooth germ.CONCLUSION HE staining of two cases of dental follicle tissues showed that the volume of dental follicle cells decreased,the nuclei were condensed,and there seemed to be cellular fibrosis.The immunohistochemical staining showed that both the dental follicle and alveolar bone tissue exhibited increased expression of periostin,decreased expression of RANKL and OPG proteins,and decreased RANKL/OPG ratio.After removing resistance,the permanent tooth germ often appears to have normal eruption.Tooth eruption disorders may be accompanied by abnormal remodeling of periostin,which affects the differentiation function of osteoclasts in the dental follicle and leads to metabolic imbalance of alveolar bone,resulting in tooth eruption disorders.Whether it is a single or full permanent tooth eruption disorder,once the coronal resistance is removed,the teeth can often erupt normally.展开更多
A new electrical toothed band brake is proposed based on the planetary gear shifting transmission.The corresponding mathematical model and the finite element model are established to investigate the braking dynamic ch...A new electrical toothed band brake is proposed based on the planetary gear shifting transmission.The corresponding mathematical model and the finite element model are established to investigate the braking dynamic characteristics and the stress distribution of brake components.According to the structural features and working principle of the brake,the braking process can be divided into a gap elimination stage,a sliding stage,a meshing stage,and a collision stage.The greater the initial speed of brake drum,the higher the impact torque in the collision stage,and the larger the stress of brake components.The ideal range of initial speed is 50-100 r/min,and the ultimate stress is 514 MPa appeared in the right brake band.This study present a wide range of possibilities for further investigation and application of the electrical toothed band brake.展开更多
基金supported by the National Key Research and Development Program of China to W.Tian (2022YFA1104400)the National Natural Science Foundation of China to T.Chen (82100959)a grant from the Sichuan Science and Technology Program to Z.Liu (2024YFFK0068)。
文摘Tooth morphogenesis is orchestrated by a complex interplay of signaling pathways and transcription factors that control cell proliferation,apoptosis,and differentiation,with the Wnt/β-catenin signaling pathway playing a pivotal role.However,the comprehensive regulatory mechanisms of Wnt/β-catenin signaling remain largely unclear.Smad7,a key antagonist of the TGF-βsuperfamily,is essential for maintaining tissue homeostasis and ensuring proper cellular function.Our previous study has demonstrated that Smad7 knockout in mice leads to impaired proliferative property of tooth germ cells,resulting in small molars.Here,we identified SMAD7 expression in human dental papilla and dental pulp,colocalized with β-CATENIN and cell proliferationrelated proteins.RNA sequencing analysis revealed a significant reduction in Wnt signaling activity in Smad7-deficient mouse tooth germs.Using lentivirus transfection,we established SMAD7-knockdown human dental papilla stem cells,which manifested remarkably blunt proliferation rate,along with diminished Wnt signaling activity.In vivo transplantation investigations further revealed the indispensable role of SMAD7 in dentin formation.Mechanistically,we revealed that β-CATENIN interacts with P-SMAD2/3 and SMAD7 through co-immunoprecipitation and yeast two-hybrid assays.Inhibition of TGF-β pathway or disruption of SMAD7/β-CATENIN transcription factor complex formation potently impacted Wnt/β-catenin activities,indicating both direct and indirect regulatory mechanisms.These findings highlight the critical role of SMAD7 in the proliferation and diffe rentiation of human dental stem cells,which could contribute to dental tissue regeneration and engineering.
文摘In order to eliminate the meshing interference between the flexspline and circular spline after the taper deformation of the flexspline,the radial deformation difference method,major and minor axis fitting method,and ellipse fitting method are used to modify the tooth thickness of the flexspline and analyze the performance indexes such as the assembly stress,transmission error,and fatigue life.Firstly,the conjugate tooth profile is solved based on the quadruple-circular-arc tooth profile and modified kinematic method.Then,based on the finite element radial deformation of the flexspline,the principle and characteristics of three modification methods are analyzed,and the modification amount of each section of the flexspline tooth is calculated.Finally,the influence of the three modification methods on the performance of the harmonic drive is compared.The results show that the radial deformation difference method can initially determine the modification amount.The minimum static assembly stress is 406.22 MPa by the major and minor axis fitting method.The ellipse fitting method has the best dynamic performance,small transmission error fluctuation,a peak-to-peak value of 3.060",and a maximum fatigue life of 10^(7.558)cycles.
基金supported by the grants No.82370912 from the National Natural Science Foundation of ChinaNo.2022020801010499 from the Bureau of Science and Technology of Wuhan,ChinaNo.2042023kf0231 from the Fundamental Research Funds for the Central Universities,China。
文摘Tooth developmental anomalies are a group of disorders caused by unfavorable factors affecting the tooth development process,resulting in abnormalities in tooth number,structure,and morphology.These anomalies typically manifest during childhood,impairing dental function,maxillofacial development,and facial aesthetics,while also potentially impacting overall physical and mental health.The complex etiology and diverse clinical phenotypes of these anomalies pose significant challenges for prevention,early diagnosis,and treatment.As they usually emerge early in life,long-term management and multidisciplinary collaboration in dental care are essential.However,there is currently a lack of systematic clinical guidelines for the diagnosis and treatment of these conditions,adding to the difficulties in clinical practice.In response to this need,this expert consensus summarizes the classifications,etiology,typical clinical manifestations,and diagnostic criteria of tooth developmental anomalies based on current clinical evidence.It also provides prevention strategies and stage-specific clinical management recommendations to guide clinicians in diagnosis and treatment,promoting early intervention and standardized care for these anomalies.
基金supported by the National Natural Science Foundation of China(Nos.62375144 and 12404345)"the Fundamental Research Funds for the Central Universities",Nankai University(No.63241331).
文摘Accurate and early evaluation of dental physiological characteristics is essential for effective disease detection and management.Polarization-sensitive optical coherence tomography(PS-OCT)is a noninvasive high-resolution imaging technique that can obtain tooth structure and physiological features through intensity,retardation and degree of polarization uniformity(DOPU)images.In this study,we use the information provided by the PS-OCT system,especially the retardation information,to assess the physiological characteristics of teeth.In addition,we introduce a novel parameter—the rate of change of the retardation value(R)—to evaluate the magnitude of birefringence of enamel,which serves as an indicator of enamel health and mineralization.The results demonstrate that PS-OCT not only provides structural detail comparable to microcomputed tomography(microCT),but also yields additional physiological characteristics insights through polarization-based contrast.These findings highlight the strong potential of PS-OCT for early diagnosis,functional evaluation and personalized monitoring in dental care.
基金Project(2024YFB3410402)supported by the National Key R&D Program of ChinaProject(52075558)supported by the National Natural Science Foundation of China+2 种基金Project(2021RC3012)supported by the Science and Technology Innovation Program of Hunan Province,ChinaProject(2023CXQD050)supported by the Central South University Innovation-Driven Research Program,ChinaProject(CX20230255)supported by the Fundamental Research Funds for the Central Universities,China。
文摘This study develops a contact performance-driven method for skiving face gear drives using a single cutter,eliminating the traditional need for separate cutters to reduce production costs and time.First,the mathematical models of the tooth flanks for the face gear drives are established based on the gear skiving processes.Then,load tooth contact analysis(LTCA)model is established to calculate the contact performance data.Next,a two-stage optimization model is employed to determine the optimal parameters of the cutting edge with improved contact performances.The effectiveness of this method is validated through simulations and rolling tests.Compared with the traditional method,the proposed method can machine both the face gear and its mating pinion with a single cutter.Simulation results show that the proposed method avoids tooth surface edge contact,with the maximum tooth surface contact stress reduced by 31.7%,the contact ratio decreases by 21.5%,and the transmission error increases by 22.3%.Rolling tests verify the consistency of tooth surface contact patterns between simulations and experiments.The proposed method provides a reference for the cutting edge design of skiving cutters for face gear pairs.
基金supported by the National Natural Science Foundation of China,Nos.82271411(to RG),51803072(to WLiu)grants from the Department of Finance of Jilin Province,Nos.2022SCZ25(to RG),2022SCZ10(to WLiu),2021SCZ07(to RG)+2 种基金Jilin Provincial Science and Technology Program,No.YDZJ202201ZYTS038(to WLiu)The Youth Support Programmed Project of China-Japan Union Hospital of Jilin University,No.2022qnpy11(to WLuo)The Project of China-Japan Union Hospital of Jilin University,No.XHQMX20233(to RG)。
文摘Nerve regeneration following traumatic peripheral nerve injuries and neuropathies is a complex process modulated by diverse factors and intricate molecular mechanisms.Past studies have focused on factors that stimulate axonal outgrowth and myelin regeneration.However,recent studies have highlighted the pivotal role of autophagy in peripheral nerve regeneration,particularly in the context of traumatic injuries.Consequently,autophagy-targeting modulation has emerged as a promising therapeutic approach to enhancing peripheral nerve regeneration.Our current understanding suggests that activating autophagy facilitates the rapid clearance of damaged axons and myelin sheaths,thereby enhancing neuronal survival and mitigating injury-induced oxidative stress and inflammation.These actions collectively contribute to creating a favorable microenvironment for structural and functional nerve regeneration.A range of autophagyinducing drugs and interventions have demonstrated beneficial effects in alleviating peripheral neuropathy and promoting nerve regeneration in preclinical models of traumatic peripheral nerve injuries.This review delves into the regulation of autophagy in cell types involved in peripheral nerve regeneration,summarizing the potential drugs and interventions that can be harnessed to promote this process.We hope that our review will offer novel insights and perspectives on the exploitation of autophagy pathways in the treatment of peripheral nerve injuries and neuropathies.
文摘Instrument separation is a critical complication during root canal therapy,impacting treatment success and long-term tooth preservation.The etiology of instrument separation is multifactorial,involving the intricate anatomy of the root canal system,instrument-related factors,and instrumentation techniques.Instrument separation can hinder thorough cleaning,shaping,and obturation of the root canal,posing challenges to successful treatment outcomes.Although retrieval of separated instrument is often feasible,it carries risks including perforation,excessive removal of tooth structure and root fractures.Effective management of separated instruments requires a comprehensive understanding of the contributing factors,meticulous preoperative assessment,and precise evaluation of the retrieval difficulty.The application of appropriate retrieval techniques is essential to minimize complications and optimize clinical outcomes.The current manuscript provides a framework for understanding the causes,risk factors,and clinical management principles of instrument separation.By integrating effective strategies,endodontists can enhance decision-making,improve endodontic treatment success and ensure the preservation of natural dentition.
基金supported by the National Natural Science Foundation of China(82071143,82371000,82270361)Key Research and Development Program of Jiangsu Province(BE2022795)+2 种基金the Postgraduate Research&Practice Innovation Program of Jiangsu Province(KYCX22_1801)the Jiangsu Province Capability Improvement Project through the Science,Technology and Education-Jiangsu Provincial Research Hospital Cultivation Unit(YJXYYJSDW4)Jiangsu Provincial Medical Innovation Center(CXZX202227).
文摘Corticotomy is a clinical procedure to accelerate orthodontic tooth movement characterized by the regional acceleratory phenomenon(RAP).Despite its therapeutic effects,the surgical risk and unclear mechanism hamper the clinical application.Numerous evidences support macrophages as the key immune cells during bone remodeling.Our study discovered that the monocyte-derived macrophages primarily exhibited a pro-inflammatory phenotype that dominated bone remodeling in corticotomy by CX3CR1CreERT2;R26GFP lineage tracing system.Fluorescence staining,flow cytometry analysis,and western blot determined the significantly enhanced expression of binding immunoglobulin protein(BiP)and emphasized the activation of sensor activating transcription factor 6(ATF6)in macrophages.Then,we verified that macrophage specific ATF6 deletion(ATF6f/f;CX3CR1CreERT2 mice)decreased the proportion of pro-inflammatory macrophages and therefore blocked the acceleration effect of corticotomy.In contrast,macrophage ATF6 overexpression exaggerated the acceleration of orthodontic tooth movement.In vitro experiments also proved that higher proportion of pro-inflammatory macrophages was positively correlated with higher expression of ATF6.At the mechanism level,RNA-seq and CUT&Tag analysis demonstrated that ATF6 modulated the macrophage-orchestrated inflammation through interacting with Tnfαpromotor and augmenting its transcription.Additionally,molecular docking simulation and dual-luciferase reporter system indicated the possible binding sites outside of the traditional endoplasmic reticulum-stress response element(ERSE).Taken together,ATF6 may aggravate orthodontic bone remodeling by promoting Tnfαtranscription in macrophages,suggesting that ATF6 may represent a promising therapeutic target for non-invasive accelerated orthodontics.
基金supported by the National Natural Science Foundation of China(No.82071078,82370939)the Shaanxi Provincial High-level Talent Program and Young Talent Support Plan of Xi’an Jiaotong University.
文摘Tissue interactions play a crucial role in tooth development.Notably,extracellular vesicle-mediated interactions between the mandible and tooth germ are considered essential.Here,we revealed that mandible extracellular vesicles could modulate the proliferation and differentiation of dental mesenchymal cells by regulating the histone demethylase KDM2B.Further investigation showed that mandible derived extracellular vesicles could deliver miR-206 to KDM2B,thereby regulating tooth development.An animal study demonstrated that the miR-206/KDM2B pathway affected tooth morphogenesis and mineralization after eight weeks of subcutaneous transplantation in nude mice.In conclusion,this study suggested that the mandible played a critical role in tooth morphogenesis and mineralization,which could be a potential therapeutic target for abnormal tooth development and an alternative model for tooth regeneration.
基金supported by grants from the National Key Research and Development Program(2022YFA1104401)CAMS Innovation Fund for Medical Sciences(2019-I2M-5-031 to Z.P.F.)grants from Innovation Research Team Project of Beijing Stomatological Hospital,Capital Medical University(NO.CXTD202204 to Z.P.F.).
文摘Dental mesenchymal stem cells(DMSCs)are pivotal for tooth development and periodontal tissue health and play an important role in tissue engineering and regenerative medicine because of their multidirectional differentiation potential and self-renewal ability.The cellular microenvironment regulates the fate of stem cells and can be modified using various optimization techniques.These methods can influence the cellular microenvironment,activate disparate signaling pathways,and induce different biological effects.“Epigenetic regulation”refers to the process of influencing gene expression and regulating cell fate without altering DNA sequences,such as histone methylation.Histone methylation modifications regulate pivotal transcription factors governing DMSCs differentiation into osteo-/odontogenic lineages.The most important sites of histone methylation in tooth organization were found to be H3K4,H3K9,and H3K27.Histone methylation affects gene expression and regulates stem cell differentiation by maintaining a delicate balance between major trimethylation sites,generating distinct chromatin structures associated with specific downstream transcriptional states.Several crucial signaling pathways associated with osteogenic differentiation are susceptible to modulation via histone methylation modifications.A deeper understanding of the regulatory mechanisms governing histone methylation modifications in osteo-/odontogenic differentiation and immune-inflammatory responses of DMSCs will facilitate further investigation of the epigenetic regulation of histone methylation in DMSC-mediated tissue regeneration and inflammation.Here is a concise overview of the pivotal functions of epigenetic histone methylation at H3K4,H3K9,and H3K27 in the regulation of osteo-/odontogenic differentiation and renewal of DMSCs in both non-inflammatory and inflammatory microenvironments.This review summarizes the current research on these processes in the context of tissue regeneration and therapeutic interventions.
基金the National Science and Technology Major Project of China(No.2019-VII0017e0158)the National Natural Science Foundation of China(No.U21A20131)+1 种基金the Industry-University Research Cooperation Project,China(No.HFZL2020CXY025)the National Key Laboratory of Science and Technology on Helicopter Transmission,China(No.HTL-O-21G05).
文摘Spiral bevel gears are critical transmission components,and are widely used in the aerospace field.This paper proposes a new multi-DOF envelope forming process for fabricating spiral bevel gears.Firstly,the multi-DOF envelope forming principle of spiral bevel gears is proposed.Secondly,the design methods for the envelope tool geometry and movement are proposed based on the envelope geometry and movement relationships.Thirdly,the metal flow and tooth filling laws are revealed through 3D FE simulation of the multi-DOF envelope forming process of a typical spiral bevel gear.Fourthly,a new method for separating the envelope tool and the formed spiral bevel gear with back taper tooth is proposed to avoid their interference.Finally,experiments on multi-DOF envelope forming of this typical spiral bevel gear are conducted using new heavy load multi-DOF envelope forming equipment.The simulation and experimental results show the feasibility of the proposed multi-DOF envelope forming process for fabricating spiral bevel gears with back taper tooth and the corresponding process design methods.
基金supported by the National Key Research and Development Program(2022YFA1104401)Beijing Municipal Government grant(Beijing Laboratory of Oral Health,PXM2021-014226-000041)+3 种基金Beijing Municipal Govemment(Beijing Scholar Program,PXM2021-014226-000020)National Natural Science Foundation of China(82030031,92149301,81991504,L2224038,82270945)Innovation Research Team Project of Beijing Stomatological Hospital,Capital Medical University(CXTD202201)Chinese Research Unit of Tooth Development and Regeneration,Academy of Medical Sciences(2019-12M-5-031).
文摘The regulatory processes in developmental biology research are significantly influenced by long non-coding RNAs(lncRNAs).However,the dynamics of lncRNA expression during human tooth development remain poorly understood.In this research,we examined the lncRNAs present in the dental epithelium(DE)and dental mesenchyme(DM)at the late bud,cap,and early bell stages of human fetal tooth development through bulk RNA sequencing.Developmental regulators co-expressed with neighboring lncRNAs were significantly enriched in odontogenesis.Specific lncRNAs expressed in the DE and DM,such as PANCR,MIR205HG,DLX6-AS1,and DNM3OS,were identified through a combination of bulk RNA sequencing and single-cell analysis.Further subcluster analysis revealed lncRNAs specifically expressed in important regions of the tooth germ,such as the inner enamel epithelium and coronal dental papilla(CDP).Functionally,we demonstrated that CDP-specific DLX6-AS1 enhanced odontoblastic differentiation in human tooth germ mesenchymal cells and dental pulp stem cells.These findings suggest that lncRNAs could serve as valuable cell markers for tooth development and potential therapeutic targets for tooth regeneration.
基金Project(2024A1515240020)supported by the Guangdong Basic and Applied Basic Research Foundation,China。
文摘The contact characteristics of the rough tooth surface during the meshing process are significantly affected by the lubrication state.The coupling effect of tooth surface roughness and lubrication on meshing characteristics of planetary gear is studied.An improved three-dimensional(3 D)anisotropic tooth surface roughness fractal model is proposed based on the experimental parameters.Considering asperity contact and elastohydrodynamic lubrication(EHL),the contact load and flexibility deformation of the tooth surface are derived,and the deformation compatibility equation of the 3 D loaded tooth contact analysis(3 D-LTCA)method is improved.The asperity of the tooth surface changes the system from EHL to mixed lubrication and reduces the stiffness of the oil film.Compared with the sun planet gear,the asperity has a greater effect on the meshing characteristics of the ring-planet gear.Compared with the proposed method,the comprehensive stiffness obtained by the traditional calculation method considering the lubrication effect is smaller,especially for the ring-planet gear.Compared with roughness,speed and viscosity,the meshing characteristics of planetary gears are most sensitive to torque.
基金co-supported by the National Natural Science Foundation of China (No. 52175104)the Postdoctoral Fellowship Program of CPSF (No. GZC20233008)
文摘Tooth cracks may occur in spiral bevel gear transmission system of the aerospace equipment.In this study,an accurate and efficient loaded tooth contact analysis(LTCA)model is developed to predict the contact behavior and time-varying meshing stiffness(TVMS)of spiral bevel gear pair with cracked tooth.The tooth is sliced,and the contact points on slices are computed using roll angle surfaces.Considering the geometric complexity of crack surface,a set of procedures is formulated to generate spatial crack and determine crack parameters for contact points.According to the positional relationship between contact point and crack path,each sliced tooth is modeled as a non-uniform cantilever beam with varying reduced effective load-bearing tooth thickness.Then the compliance model of the cracked tooth is established to perform contact analysis,along with TVMS calculations utilizing three different models.By employing spiral bevel gear pairs with distinct types of cracks as examples,the accuracy and efficiency of the developed approach are validated via comparative analyses with finite element analysis(FEA)outcomes.Furthermore,the investigation on effects of cracks shows that tooth cracks can induce alterations in meshing performance of both entire gear pair and individual tooth pairs,including not only cracked tooth pair but also adjacent non-cracked tooth pairs.Hence,the proposed model can serve as a useful tool for analyzing the variations in contact behavior and meshing stiffness of spiral bevel gears due to different cracks.
基金the National Natural Science Foundation of China(U22A20314,82470988,32070826)National Key R&D of Program of China(2022YFC2504201)+2 种基金Outstanding Youth Fund of Chongqing Natural Science Foundation(CSTB2023NSCQJQX0006)Science and Technology Research Project of Chongqing Education Commission(KJQN202200471)CQMU Program for Youth Innovation in Future Medicine(W0075).
文摘The repair of the periodontal membrane is essential for the successful management of periodontal disease and dental trauma.Emdogain®(EMD)is widely used in periodontal therapy due to its ability to promote repair.Despite substantial research,the cellular and molecular mechanisms underlying EMD’s effects,particularly at the single-cell resolution,remain incompletely understood.This study established a delayed tooth replantation model in rats to investigate these aspects.Tooth loss rate and degree of loosening were evaluated at 4 and 8 weeks.Micro-CT,HE staining,TRAP staining,and immunofluorescence staining were evaluated to assess EMD’s efficacy.Single-cell sequencing analyses generated single-cell maps that explored enrichment pathways,cell communication,and potential repair mechanisms.Findings indicated that EMD could reduce the rate of tooth loss,promote periodontal membrane repair,and reduce root and bone resorption.Single-cell analysis revealed that EMD promotes the importance of Vtn+fibroblasts,enhancing matrix and tissue regeneration functions.Additionally,EMD stimulated osteogenic pathways,reduced osteoclastic activity,and promoted angiogenesis-related pathways,particularly bone-related H-type vessel expression in endothelial cells.Gene modules associated with angiogenesis,osteogenesis,and odontoblast differentiation were identified,suggesting EMD might facilitate osteogenesis and odontoblast differentiation by upregulating endothelium-related genes.Immune cell analysis indicated that EMD did not elicit a significant immune response.Cell communication analysis suggested that EMD fostered pro-regenerative networks driven by interactions between mesenchymal stem cells,fibroblasts,and endothelial cells.In conclusion,EMD proves to be an effective root surface therapy agent that supports the restoration of delayed replantation teeth.
文摘Intentional tooth replantation(ITR)is an advanced treatment modality and the procedure of last resort for preserving teeth with inaccessible endodontic or resorptive lesions.ITR is defined as the deliberate extraction of a tooth;evaluation of the root surface,endodontic manipulation,and repair;and placement of the tooth back into its original socket.Case reports,case series,cohort studies,and randomized controlled trials have demonstrated the efficacy of ITR in the retention of natural teeth that are untreatable or difficult to manage with root canal treatment or endodontic microsurgery.However,variations in clinical protocols for ITR exist due to the empirical nature of the original protocols and rapid advancements in the field of oral biology and dental materials.This heterogeneity in protocols may cause confusion among dental practitioners;therefore,guidelines and considerations for ITR should be explicated.This expert consensus discusses the biological foundation of ITR,the available clinical protocols and current status of ITR in treating teeth with refractory apical periodontitis or anatomical aberration,and the main complications of this treatment,aiming to refine the clinical management of ITR in accordance with the progress of basic research and clinical studies;the findings suggest that ITR may become a more consistent evidence-based option in dental treatment.
文摘Background: Tooth loss results in impaired mastication, which in turn, makes it difficult to chew hard food, consequently leading to deteriorate dietary habits and to develop hypertension. The purpose of this study was to examine the effect of tooth loss on blood pressure among Congolese population. Methods: A cross-sectional study was conducted from October 2019 until December 2023 among Congolese population aged at least 30 years reporting to the living in DR Congo. All participants were enrolled from Dental Clinic located in the DR Congo. To be eligible to participate in the study, were the willing to participate and having signed informed consent;had a missing tooth;had carried out blood pressure measurement (hypertension/normotensive). The exclusion criteria were determined: being less than 30 years old, being pregnant for women considering the risk of existing gestational hypertension, obesity, excessive alcohol consumption, smoking, and diabetes. Hypertension was defined as the mean of three measurements of systolic blood pressure (SBP) (140 mmHg or higher), diastolic blood pressure (DBP) (90 mm or higher) or physician diagnosed hypertension confirmed from medical records. We determined the number of tooth loss from oral examination. A multivariable logistic regression model was used to investigate the effect of tooth loss on blood pressure. Results: In all, 25,396 participants were enrolled among Congolese population for this study. After oral examination, 13,421 were excluded for no tooth loss and 11,975 participants were selected. The average number of tooth loss among study population was 11.06. Among the participants with hypertension had lost an average of 11 teeth, significantly higher than those without hypertension (6.09) (p = 0.001). After adjusting for covariates (socio-demographic characteristics), tooth loss (>10) was significantly associated with hypertension, with OR = 1.32 (95% CI 1.073 - 2.38). Conclusion: Tooth loss maybe associated with severe hypertension among Congolese population adults. Prevention of tooth loss is very important to the overall health of this population.
基金Supported by The Xuzhou Medical University Affiliated Hospital Development Fund Support Project,No.XYFM202457the 521 Scientific Research Project of Lianyungang City,No.LYG 06521202362.
文摘BACKGROUND This study analyzed the dental follicle and alveolar bone of two patients with tooth eruption disorders,aiming to provide some reference for exploring the etiology and selecting treatment plans of this disease from the perspective of the influence of extracellular matrix on osteoclasts differentiation in dental follicle.CASE SUMMARY Collect dental follicle and alveolar bone tissue from one patient with single tooth eruption disorder and one patient with full permanent tooth eruption disorder,respectively.Simultaneously collect the dental follicle and alveolar bone tissue of obstructed teeth that need to be extracted due to orthodontic treatment as the control group.Hematoxylin and eosin(HE)staining was used to observe the morphology of dental follicle cells.Immunohistochemical staining was used to observe the expression of periostin,receptor activator of nuclear factor kappa B ligand(RANKL),and osteoprotegerin(OPG)protein in dental follicle and alveolar bone tissue.And observe the eruption of teeth after removing resistance from the crown of the permanent tooth germ.CONCLUSION HE staining of two cases of dental follicle tissues showed that the volume of dental follicle cells decreased,the nuclei were condensed,and there seemed to be cellular fibrosis.The immunohistochemical staining showed that both the dental follicle and alveolar bone tissue exhibited increased expression of periostin,decreased expression of RANKL and OPG proteins,and decreased RANKL/OPG ratio.After removing resistance,the permanent tooth germ often appears to have normal eruption.Tooth eruption disorders may be accompanied by abnormal remodeling of periostin,which affects the differentiation function of osteoclasts in the dental follicle and leads to metabolic imbalance of alveolar bone,resulting in tooth eruption disorders.Whether it is a single or full permanent tooth eruption disorder,once the coronal resistance is removed,the teeth can often erupt normally.
基金funded by the National Natural Science Foundation of China(Nos.52205047,52175037)China Postdoctoral Science Foundation(No.2021M700422)Beijing Key Laboratory Foundation(No.KF20212223201).
文摘A new electrical toothed band brake is proposed based on the planetary gear shifting transmission.The corresponding mathematical model and the finite element model are established to investigate the braking dynamic characteristics and the stress distribution of brake components.According to the structural features and working principle of the brake,the braking process can be divided into a gap elimination stage,a sliding stage,a meshing stage,and a collision stage.The greater the initial speed of brake drum,the higher the impact torque in the collision stage,and the larger the stress of brake components.The ideal range of initial speed is 50-100 r/min,and the ultimate stress is 514 MPa appeared in the right brake band.This study present a wide range of possibilities for further investigation and application of the electrical toothed band brake.
