BACKGROUND:One of the advantages of clear aligner treatment is molar distalization.However,tooth tilting movement and loss of anterior anchorage may occur during treatment.There are few studies on whether these problems can be improved by selecting clear aligners with different thicknesses and edges to improve the clinical treatment effect.OBJECTIVE:To analyze the control ability of clear aligners with different thickness and edges on the central incisor,lateral incisor,and second molar when pushing the maxillary second molar distally by three-dimensional finite element analysis.METHODS:Three-dimensional finite element analysis models of bilateral maxillary second molar distalization with clear aligner,maxillary dentition,periodontal ligament,and alveolar bone with different thicknesses and margins were established by Mimics,Geomagic Wrap,3-matic and SolidWorks software,respectively.There were 16 combinations of four thicknesses(0.4,0.5,0.625,and 0.75 mm)and four margins(scallop,straight,straight extension 2 mm and straight extension 4 mm).The data were imported into Ansys Workbench software for design and solution.The mean value,peak value and distribution of the periodontal ligament equivalent stress of the second molar,the equivalent stress and the maximum initial displacement of the second molar,and the control ability of each appliance on the second molar,central incisor,and lateral incisor were analyzed.RESULTS AND CONCLUSION:(1)The mean equivalent stress of periodontal ligament of the second molar,the equivalent stress of the second molar and the maximum initial displacement of the second molar increased with the extension of the appliance edge and the increase of the thickness of the appliance in the 16 groups of models.(2)When the thickness of appliances was the same,the maximum equivalent stress of the second molar in the linear appliance group was the highest,and the maximum equivalent stress of the second molar in the linear extended appliance group was greater than that in the scallop appliance group.When the edge of the appliance was the same,the periodontal ligament equivalent stress peak of the second molar increased with the increase of the thickness of the appliance.The equivalent stress distribution in the periodontal ligament of the second molar in the linear extendable appliance group was more uniform than that in the scallop appliance group and the linear appliance group.(3)When the thickness of the appliance was the same,the scallop-shaped appliance had the worst control on the second molar.When the edge of the appliance was the same,with the increase of the thickness of the appliance,the control of the second molar by the linear extender appliance was gradually stronger than that by the linear appliance.The control of the central incisor was stronger and more stable with the linear extended 2 mm appliance,while the control of the lateral incisor was stronger and more stable with the linear appliance.(4)The results showed that when using clear aligners to push molars distally,extending the edge of the appliance could improve the control of the molars and reduce the tilting movement of the teeth.The design of a straight extension margin of 2 mm for the central incisor and a straight edge for the lateral incisor can enhance the control of the anchorage incisor and reduce the labial inclination of the anterior teeth.

BACKGROUND:Titanium elastic intramedullary nailing for the treatment of significantly displaced midshaft clavicle fractures has the characteristics of minimally invasive and elastic fixation.The displacement of the fracture is closely related to the later function.However,there are few studies on the three-dimensional displacement analysis of the fracture ends before surgery and after intramedullary fixation such as titanium elastic intramedullary nailing.OBJECTIVE:To explore the three-dimensional displacement of fracture ends after midshaft clavicle fracture and fixation with titanium elastic intramedullary nails,and to analyze the risk factors.METHODS:A total of 91 patients with midshaft clavicle fracture(fracture end shortening ≥15 mm)admitted to Wendeng Orthopedic Hospital of Shandong Province from April 2019 to April 2024 were selected,including 57 males and 34 females,aged(51.73±10.21)years old.All patients received closed reduction and internal fixation with titanium elastic intramedullary nail.CT scans of the affected clavicle were performed before and on the first day after surgery.The CT data were imported into Mimics software for modeling.The length of the clavicle,lateral displacement of the fracture end,and rotation of the distal end of the fracture along the X,Y,and Z axes were measured and recorded before and after surgery.Pearson correlation coefficient was used for correlation analysis of various parameters,and generalized linear regression was used to evaluate risk factors.RESULTS AND CONCLUSION:(1)Preoperatively,the variable that increased the risk of lateral displacement was the number of comminuted bone fragments,the variable that increased the risk of shortening displacement was male patients,and the variable that increased the risk of Z-axis rotation was the left limb.Shortening displacement was significantly positively correlated with lateral displacement(r=0.715,P＜0.001);shortening displacement was significantly positively correlated with X-axis rotation displacement and Y-axis rotation displacement(r=0.265,P=0.028;r=0.303,P=0.011);lateral displacement was significantly positively correlated with Y-axis rotation and Z-axis rotation(r=0.258,P=0.032;r=0.250,P=0.038);X-axis rotation was significantly positively correlated with Y-axis rotation(r=0.382,P=0.001),and Z-axis rotation was significantly positively correlated with Y-axis rotation(r=0.280,P=0.020).(2)Postoperatively:The number of scapula fractures and comminuted bone fragments were variables that increased the risk of postoperative shortening and lateral displacement:Preoperative X-,Y-,and Z-axis rotation displacements were risk variables that increased postoperative X-,Y-,and Z-axis rotation displacements,respectively.Postoperative lateral displacement was significantly positively correlated with postoperative shortening and displacement(r=0.584,P=0.000),and postoperative lateral displacement was also significantly positively correlated with postoperative Y axis rotation and Z axis rotation(r=0.360,P=0.002;r=0.250,P=0.038).Postoperative Y axis rotation was significantly positively correlated with postoperative Z axis rotation(r=0.248,P=0.040).(3)The results showed that the three-dimensional displacement of the clavicle end before and after surgery was affected by many factors,especially the number of comminuted bone fragments,scapula fractures,gender,and original rotation displacement.At the same time,there were complex correlations between various displacements,especially the correlation between shortening displacement and lateral displacement was the strongest.

BACKGROUND:Orthodontic treatment to move the mandibular second molar in place of the missing first molar is a good method for preserving natural teeth.However,molars often exhibit mesial tipping when using clear aligners.The impact of attachments and overcorrection on the molar mesialization with clear aligners is unclear.OBJECTIVE:To investigate the effects of attachments and overcorrection on displacement and biomechanics of the mandibular second molar mesialization.METHODS:A finite element model with the left mandibular first molar missing was constructed using a volunteer's cone-beam CT and intraoral scan data.The experiment was divided into four groups based on the position of attachments on the left mandibular second molar:without attachment,buccal attachment,lingual attachment,and buccal-lingual attachment,with overcorrection degrees(0°,1°,2°,3°,and 4°)for each group,totaling 20 models.The calculation and analysis of the displacement trends and stress were performed using Abaqus software.RESULTS AND CONCLUSION:(1)Mesial tipping and intrusion of the molar,distal tipping of the canines and permolars,and linguaing of the incisors occurred during molar mesialization.(2)The displacement of molars increased when attachments were used,with the maximum displacement occurring when buccal-lingual attachments were applied.Molars tended to tip towards the side without attachments when attachments were designed unilaterally.However,the inclination of molars did not decrease when attachments were used.(3)Molars exhibited reduced mesial tipping and intrusion,approaching overall movement,and the stress of periodontal ligament was relieved and more evenly distributed during overcorrection treatment,and this effect became more pronounced with increased degrees of overcorrection.(4)Attachments can enhance the effectiveness of overcorrection,with the best performance observed when buccal-lingual attachments are used.Using attachments and overcorrection together helps control molar mesial tipping and intrusion,but overall molar movement is not achieved.

BACKGROUND:Low temperatures have detrimental effects on the human cardiovascular system,with a higher prevalence of hypertension and related cardiovascular diseases,especially among people living in cold climates.Transient receptor potential M8(TRPM8)is often recognized as a physiological sensor of environmental cold,and glutamate receptor-3(GLR-3)/glutamate receptor ionotropic,kainate 2(GluK2)is also cold-sensitive.However,the specific molecular mechanisms of cold-associated TRPM8 and GLR-3/GluK2 in regulating hypertension remain puzzling.OBJECTIVE:Through a review of the literature in this field,to find out the general pattern of TRPM8 and GLR-3/GluK2 in regulating the body's cold response,as well as the specific mechanism of action in hypertension,thereby providing a theoretical basis for subsequent research on the treatment of hypertension based on cold-stimulation-related targets,and further expanding the new ideas and methods for the treatment of hypertension.METHODS:We searched,reviewed and screened the relevant literature on"cold stimulation,TRPM8,GLR-3/GluK2 and hypertension"to lay the theoretical foundation for the analysis of the whole article.Comparative analysis method,through reading and analyzing the obtained literature,comparing the similarities and differences between the literature,was performed to provide reasonable theoretical support for the argument.Through further comparative analysis of the literature,the relationship between the relevant indicators was clarified,and the ideas were clarified for the analysis of the full text.RESULTS AND CONCLUSION:(1)TRPM8 can be activated by cold and mainly mediates cool temperature perception in mammals.Its activation can trigger neurogenic inflammatory response and indirectly affect the inflammatory process.Abnormal TRPM8 signal can lead to excessive activation of immune cells,which is significantly associated with the occurrence and development of hypertension.(2)The activation threshold of GLR-3/GluK2 is lower than that of TRPM8,which may preferentially respond to noxious cold stimulation rather than ordinary cool temperature.In cold environment,GLR-3/GluK2 activation enhances sympathetic nerve excitability by regulating interneuron signal transduction and causes peripheral vascular constriction.Long-term effects can lead to increased peripheral vascular resistance.To conclude,TRPM8 and GLR-3/GluK2 are involved in the interaction of the nerve-immune-vascular system by sensing different cold stimuli.Abnormal TRPM8 signaling indirectly promotes the progression of hypertension through inflammation and immune dysregulation,while GLR-3/GluK2 directly exacerbates vascular constriction and resistance by enhancing sympathetic nerve activity.The combination of the two factors may constitute the key molecular mechanism of the occurrence and development of hypertension in cold environment,and provide a potential target for the intervention of cold-related cardiovascular diseases.

BACKGROUND:Maxillofacial bone three-dimensional(3D)printing technology has been widely used in clinical diagnosis and treatment,but the data source before performing maxillofacial bone 3D printing mainly comes from the CT scanning data.The lens,thyroid and other parts of the human body are extremely sensitive to X-rays;therefore,it is particularly important to effectively reduce the dose of CT radiation when acquiring the data source.OBJECTIVE:To explore the feasibility of low-dose CT technology in optimizing radiation dose for maxillofacial bone 3D printing.METHODS:The medical records of 65 patients who underwent maxillofacial bone 3D printing in the Department of Stomatology at the General Hospital of Northern Theater Command from March 2021 to December 2023 were retrospectively collected and categorized into a conventional CT-dose 3D printing group(conventional CT-dose,120 kVp,automated tube current modulation,n=32)and a low-CT-dose 3D printing group(low-CT-dose group,80 kVp,automated tube current modulation,n=33).The effective dose of radiation was calculated and compared between the two groups.A Likert scale was used to evaluate the quality of 3D printing in the two groups,and the measurement bias and consistency between evaluators were measured using the Bland-Altman method.RESULTS AND CONCLUSION:(1)There was no significant difference in the general demographic characteristics(age,height,weight,body mass,sex,and body mass index)between the two groups(all P＞0.05).(2)The effective dose value of the low CT-dose 3D printing group was(0.3±0.1)mSv,which was about 62.5％lower than that in the conventional CT-dose 3D printing group[(0.8±0.1)mSv].(3)There was no significant difference in the subjective scoring of 3D printing quality between the two groups(all P＞0.05).The subjective consistency among evaluators was good,with Kappa values of 0.85,0.80,and 0.76.The scatter points in the Bland-Altman for both protocols were uniformly distributed within the standard deviation line,indicating good consistency between the two groups.To conclude,low-dose CT technology can be effectively applied in maxillofacial bone 3D printing,reducing radiation dose without affecting the quality of 3D printing.

BACKGROUND:Rapid and accurate segmentation of brain tissue in medical images is of great significance for three-dimensional biomechanical modeling and diagnosis of craniocerebral injuries.Currently,artificial intelligence(AI)-based baseline models exhibit excellent generalization capabilities on large-scale datasets.However,due to the specificity and complexity of craniocerebral tissues,these models have certain limitations in their application to craniocerebral tissue segmentation.Additionally,the scarcity of craniocerebral tissue samples makes it difficult for baseline models to achieve precise segmentation results through fine-tuning.OBJECTIVE:To construct a craniocerebral tissue segmentation model based on texture feature retrieval enhancement to improve segmentation accuracy under a small number of samples.METHODS:Segment Anything in Medical Images(MedSAM)model was selected as the basic framework,and texture features were combined with deep learning to build a brain tissue segmentation model based on texture feature retrieval enhancement(DP-MedSAM).Dice Coefficient and mean intersection over union(MIoU)were selected to evaluate the efficiency of image segmentation results.In comparison with the original MedSAM model,the ablation experiment systematically evaluated the influence of key components on the model performance.The sensitivities of MedSAM,the Segment Anything Model(SAM)for medical image segmentation(SAM-Med2D)and DP-MedSAM in the mandible,left optic nerve,and left parotid gland were compared.RESULTS AND CONCLUSION:(1)By verifying the impact of the number of point prompts on segmentation results on the HaN-Seg dataset,the experimental results indicated that the optimal Dice score was achieved with the addition of three points.(2)DP-MedSAM demonstrated performance improvements compared with MedSAM and SAM-Med2D on two datasets(HaN and Public Domain Database for Computational Anatomy).Especially on the Public Domain Database for Computational Anatomy dataset,in terms of the MIoU metric,DP-MedSAM outperformed MedSAM by 6.59％and SAM-Med2D by 37.35％;in terms of the Dice metric,DP-MedSAM outperformed MedSAM and SAM-Med2D by 4.34％and 25.32％,respectively.(3)The ablation experiment results showed that removing the texture feature extraction module in the DP-MedSAM model,relying solely on original image features,led to a significant decrease in results on the test set.Furthermore,removing the vector cache database and its retrieval enhancement function from the model,which deprived the ability of the model to perform similarity retrieval using an external knowledge base,further reduced model performance.(4)Under conditions of limited data resources,the DP-MedSAM model outperformed the other two models in all evaluation metrics.The DP-MedSAM model performed excellently when processing simple and moderately difficult samples,demonstrating a clear advantage over the other two models and indicating good generalization ability.Processing the fine structures of difficult samples placed higher demands on the model's segmentation capabilities.Although the performance of the DP-MedSAM model declined slightly,it still outperformed the other two models.(5)This study proposes an innovative craniocerebral tissue segmentation model,DP-MedSAM,which improves the baseline model's performance in capturing local details and global structural information in medical images by introducing target region texture feature extraction.Through vector similarity retrieval technology,DP-MedSAM can retrieve the feature vector most similar to the current target region from a pre-constructed vector database,providing more precise guiding information for the segmentation process.

BACKGROUND:Cell-free therapy is a research hotspot in the field of medical cosmetic anti-aging.It is still unknown for paracellular secretion of human umbilical cord mesenchymal stem cell-derived small extracellular vesicles loaded with the antiaging drug α-ketoglutaric acid to delay skin aging.OBJECTIVE:To investigate the effect of the anti-aging agent α-ketoglutarate engineered human umbilical cord mesenchymal stem cell-derived small extracellular vesicles in a D-galactose-induced model of dermal fibroblast senescence.METHODS:(1)Biological characteristics of primary human umbilical cord mesenchymal stem cells were identified by osteogenic-lipogenic differentiation staining and flow cytometry.(2)The small extracellular vesicles derived from human umbilical cord mesenchymal stem cell were obtained by using differential-ultracentrifugation.α-Ketoglutarate-engineered human umbilical cord mesenchymal stem cell-small extracellular vesicles were constructed by electroporation,and biologically characterized by transmission electron microscopy and nanoparticle tracking analyzer,while the encapsulation rate was assessed using high-performance liquid chromatography.(3)The effect of α-ketoglutarate on the proliferative capacity of dermal fibroblasts was assessed by CCK-8 and Edu cell proliferation assay kits.(4)The effect of α-ketoglutarate-engineered human umbilical cord mesenchymal stem cell-small extracellular vesicles on delaying the senescence of dermal fibroblasts was evaluated by reactive oxygen species detection kit,western blot assay,and cellular immunofluorescence.RESULTS AND CONCLUSION:(1)The obtained human umbilical cord mesenchymal stem cell and human umbilical cord mesenchymal stem cell-small extracellular vesicles were biologically compatible.(2)There was no toxic effect on dermal fibroblasts when α-ketoglutarate was used in the concentration range of 0.5-8 mmol/L.(3)D-gal induced senescence in dermal fibroblasts,while α-ketoglutarate-engineered human umbilical cord mesenchymal stem cell-small extracellular vesicles treatment reduced the level of oxidative stress,DNA damage,and collagen loss,which was further verified that α-ketoglutarate-engineered human umbilical cord mesenchymal stem cell-small extracellular vesicles could effectively slow down the skin aging process.

BACKGROUND:3D-printed bone tissue engineering scaffolds have obvious advantages in the research and clinical treatment of bone defect repair.As one of the important raw materials for 3D printed bone scaffolds,poly-L-lactic acid has a great potential for application in performing bone defect repair,but clinical patients with different bone defect causative factors have different requirements for the comprehensive performance of poly-L-lactic acid bone scaffolds.OBJECTIVE:To summarize and review the development of 3D printing technology and poly-L-lactic acid scaffolds and the design strategies chosen for scaffolds for bone repair in the setting of bone diseases such as osteomyelitis,bone tumor,osteonecrosis,and osteoporosis.METHODS:Literature from CNKI,WanFang,PubMed,Science Direct,and Web of Science databases were searched and screened from 1994 to 2024.Search terms were"3D printing,polylactic acid,bone tissue engineering scaffold,osteomyelitis,bone tumor,osteonecrosis,osteoporosis,bone defect"in Chinese and English.The screened 62 articles were systematically summarized and analyzed.RESULTS AND CONCLUSION:(1)Poly-L-lactic acid is considered to be an ideal raw material for artificial bone scaffold design due to its non-toxicity,processability,biocompatibility,and ability to self-degrade in the human environment.The application of 3D printing technology has enabled poly-L-lactic acid bone scaffolds to meet the multilayered and porous structural design requirements of biomimetic artificial bone repair materials,and to optimize the mechanical properties for better bone repair.(2)According to different bone disease microenvironments,timely adjustment of the functional design of poly-L-lactic acid scaffolds is important for the comprehensive osteogenic efficacy of the scaffolds.The article discusses the application of poly-L-lactic acid scaffolds in bone disease environments such as osteomyelitis,bone tumor,osteonecrosis,and osteoporosis,and highlights the importance of rationally grasping the timing of bone disease treatment and bone tissue regeneration for bone defects caused by different bone diseases.(3)Although poly-L-lactic acid scaffolds show potential in bone repair,there are still some problems,such as the need to further optimize the structural design of the scaffolds to fit new bone regeneration,enhance the bioactivity of the scaffolds,and take into account other functions(e.g.,antimicrobial,anti-tumor,and anti-osteoporosis)in order to adapt to the needs of bone tissue repair in different pathological environments.

BACKGROUND:Inter-limb asymmetry is a common phenomenon observed during human growth and development.Prolonged specialized training can lead to specific adaptations in inter-limb asymmetry among athletes.OBJECTIVE:To review the formation causes,manifestations,and impacts of inter-limb asymmetry on sports performance,and provide an overview of the relevant assessment methods and intervention strategies.METHODS:A literature search was conducted in the CNKI,WanFang,PubMed,and Web of Science databases from their inception to September 2024.The search terms included"asymmetry,asymmetries,asymmetric,asymmetrical,imbalance,strength,power,force,jump,sprint,athletic performance,anthropometry,injury"in English and Chinese.After excluding duplicate publications,irrelevant content,and conference papers,a total of 131 articles were finally included for analysis.RESULTS AND CONCLUSION:(1)Inter-limb asymmetry can be influenced by various factors including genetics,task demands,training regimens,injuries,fatigue,and limb preference.These factors lead to being primarily manifested in anatomical structure,strength performance,and task-specific asymmetry.(2)An increase in inter-limb asymmetry can result in impaired performance in bilateral in-phase symmetric movements.However,the relationship between increased inter-limb asymmetry and bilateral out-of-phase symmetric movements remains unclear and requires further investigation.(3)Training interventions have been shown to effectively mitigate inter-limb asymmetry,with unilateral training demonstrating superior outcomes compared with bilateral training.The choice of training methods and content should be tailored to meet the specific demands of the sport.(4)To further clarify the relationship between inter-limb asymmetry and athletic performance,it is recommended that future research adopt the concept of"task specificity"in inter-limb asymmetry.This includes standardizing study designs,selecting sensitive testing methods and indicators,unifying calculation methods to provide more high-quality evidence,and establishing categorized warning threshold standards for inter-limb asymmetry in different sports.

BACKGROUND:Spondylolisthesis is a common disease,and there is a lack of effective drugs to treat it.There is still a need to further define the pathogenesis and screen out more suitable therapeutic targets for spondylolisthesis.Mendelian randomization analysis can be used to explore the drugable genes associated with spondylolisthesis and provide valuable guidance for the development of more effective and targeted therapeutic drugs.OBJECTIVE:To explore potential therapeutic targets and effective drugs for spondylolisthesis by means of pharmaceutically available genome-wide Mendelian randomization analysis.METHODS:Using the Finnish database,eQTLGen consortium,drug signature database,drug-gene interaction database,protein-protein interaction database,organic small molecule biological activity database and protein structure database,which contains genome and health information of half a million Finns,data on druggable genes were subjected to two-sample Mendelian randomization analysis and co-localization analysis with data from genome-wide association studies of spondylolisthesis to identify genes highly associated with spondylolisthesis.In addition,GO and KEGG enrichment analysis,protein network construction,drug prediction and molecular docking were performed to provide valuable guidance for the development of more effective and targeted therapeutic agents.RESULTS AND CONCLUSION:In this study,we identified 34 potential drug target genes that were significantly associated with spondylolisthesis,particularly the gene APOBEC3G.This gene showed a significant association with spondylolisthesis outcomes through Mendelian analysis and co-localization analysis,suggesting that APOBEC3G may be a priority therapeutic target.As for other potential mechanisms and drugs,we still need to conduct more in-depth research to determine their roles.This study used a database from a European population,which can be used as a reference for the study of population genetics in China.