BACKGROUND:Arthroscopic anchor repair has become the main treatment method for rotator cuff tears at present.Among them,the insertion status of the anchor is a key factor in the success or failure of the operation.However,currently,the impact of the insertion depth of the anchor on the stress of the bone tunnel and the anchor under different bone density conditions remains unclear.OBJECTIVE:To explore the stress distribution of the bone tunnel and the anchor when the insertion depth of the anchor varies under different bone density conditions by using three-dimensional finite element analysis technology.METHODS:The CT image data of the humerus of volunteers were collected,and the models of the humerus and the anchor were constructed by using Mimics,3-Matic,and Solidworks software.In 3-Matic,holes with distances of 0,2,4,6,and 8 mm from the surface of the humerus were respectively created at the same position of the humerus and assembled with the anchor.In Mimics,values were assigned based on the CT gray value to obtain a model with normal bone mass(T value ≥-1.0).The parameters were changed to construct models with reduced bone mass(-2.5＜T value＜-1.0)and osteoporosis(T value＜-2.5).In each model,a 70 N pulling force was applied to the anchor along the direction tangent to the inner edge of the bone tunnel.The stress distribution and magnitude of the bone tunnel and the anchor when inserted at different depths under different bone density conditions were observed.RESULTS AND CONCLUSION:(1)When the insertion depth was the same,as the bone density decreased,the maximum equivalent stress of the anchor increased,while the maximum equivalent stress of the bone tunnel decreased.(2)When the bone density was the same,as the insertion depth of the anchor increased,the maximum equivalent stress of the anchor decreased.When the insertion depth was 4 mm,the stress of the bone tunnel was the smallest and the distribution was relatively uniform.The stress of the anchor was mainly distributed around the lower anchor hole and the proximal thread,and the stress of the bone tunnel was mainly at the part in contact with the proximal thread.The increase in the insertion depth would change the uniformity and pattern of the stress distribution,while the bone density had a relatively small impact on the stress distribution pattern.(3)It is concluded that the bone density of the humerus is crucial for the anchor repair of rotator cuff tears.It is recommended that clinicians measure the bone density of the greater tuberosity of the humerus before the operation.Excessive insertion depth of the anchor does not significantly increase its stability.Clinicians can conduct personalized preoperative assessments by using the finite element analysis method in combination with the actual situation of patients to achieve the best surgical results.

BACKGROUND:The quadriceps strength of patients with osteoporosis and sarcopenia is significantly reduced,which can further reduce the function of the knee joint,affect the function of the lower limbs and even lead to a decrease in whole-body coordination.It is speculated that a reasonable quadriceps training program and personalized guidance are beneficial to the recovery of knee joint function in patients with osteoporosis and sarcopenia.OBJECTIVE:To observe the effect of short-term moderate-intensity resistance rehabilitation training on the mass and function of the quadriceps and knee joint function in patients with osteoporosis and sarcopenia.METHODS:Using the integrated physical examination and rehabilitation model,375 patients with osteoporosis and sarcopenia were screened at the Health Management Center of Shanghai Public Health Clinical Center.They underwent 12 weeks of combined/comprehensive exercise rehabilitation based on resistance exercise,including quadriceps resistance isotonic and isometric contraction training twice a week(3-5 sets each time,10-15 minutes per set)and aerobic exercise/balance exercise two or three times a week(30 minutes each time).Assessments and data collection were performed before rehabilitation training,12 weeks after rehabilitation training,and at follow-up 12 weeks after stopping rehabilitation training,mainly including knee joint range of motion and proprioception,quadriceps muscle strength,and cross-sectional area(magnetic resonance imaging results),pain,knee joint function(Hospital for Special Surgery score)and walking function("up-and-go"time and 6 m pace test results)as well as the patient's psychological status assessment.RESULTS AND CONCLUSION:All 375 patients completed 12 weeks of rehabilitation training and 12 weeks of follow-up without any adverse events.(1)Compared with before training,the patients' gait speed and knee range of motion increased significantly after 12 weeks of rehabilitation training(P＜0.01),the time of"stand-to-walk"decreased(P＜0.01),and the proprioception of the knee joint and the strength of the quadriceps femoris were significantly improved(P＜0.01);and at the follow-up visit 12 weeks after stopping training,the above indicators and functions of the patients were well maintained(P＞0.05).(2)Magnetic resonance imaging results showed that the effective cross-sectional area of the quadriceps femoris did not improve significantly after 12 weeks of rehabilitation training(P＞0.05);but the Hospital for Special Surgery score of knee joint function increased significantly(P＜0.01),and the visual analog pain scale score decreased significantly(P＜0.01),suggesting that this may be related to the improvement of quadriceps femoris quality by resistance rehabilitation training.(3)The results of the Hospital Anxiety and Depression Scale score showed that the anxiety and depression scores of the patients continued to decrease,both at 12 weeks of rehabilitation training and at 12 weeks after stopping training(P＜0.01).It is suggested that resistance rehabilitation training of the quadriceps can help patients with osteoporosis and sarcopenia to restore quadriceps muscle strength,increase range of motion,improve proprioception and joint stability,thereby enhancing knee joint function,reducing pain,improving depression and anxiety,and to a certain extent promoting the coordinated recovery of the musculoskeletal system.

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:Previous studies have found that neuronal damage caused by continuous excessive fluoride exposure is related to Ca2+overload,but the mechanism of Ca2+flow conversion between intracellular calcium stores and cell apoptosis damage is still unclear.OBJECTIVE:To investigate the effect of fluoride exposure on Ca2+transport channel proteins and apoptosis levels in the mitochondria-associated endoplasmic reticulum membrane of primary cultured neural cells.METHODS:Primary nerve cells of neonatal SD rats were cultured in vitro and identified by immunofluorescence staining with neuronal nucleus-specific antibody up to day 7.The nerve cells were divided into control group(containing 0 mmol/L sodium fluoride),low fluoride group(containing 0.5 mmol/L sodium fluoride),and high fluoride group(containing 1 mmol/L sodium fluoride).The cell morphological changes were observed by light microscope 24 hours after fluorine exposure.The expression levels of apoptosis-related protein BAX/BCL-2 and calcium transfer-related pathways VDAC1,GRP 75,and IP3R were detected using western blot assay.The expression levels of VDAC1,GRP 75,and IP3R mRNA were detected by RT-PCR.Ca2+levels were detected by Rhood-2AM Ca2+probe.Mitochondrial membrane potential detection kit was used to detect the change in mitochondrial membrane potential.The level of apoptosis was determined by flow cytometry and TUNEL staining.RESULTS AND CONCLUSION:(1)The purity of neurons cultured on day 7 had been determined to be over 90％,with few impurities,good growth status,and tight cell network connections,meeting the requirements of subsequent experiments.(2)Compared with the control group,growth of neural cell clusters in the low-fluoride group and the high-fluoride group increased;the processes were broken;the cell body was rounded,and the connection network between cells was destroyed.Compared with the low-fluoride group,the cell damage changes in the high-fluoride group were more obvious.(3)Compared with the control group,the protein expressions of VDAC1,GRP75,and IP3R were increased in the low-fluoride group and the high-fluoride group(P＜0.05),and the ratio of apoptosis-related protein BAX/BCL-2 was increased(P＜0.05).Compared with the control group,the expression of VDAC1 and GRP75 mRNA in the low-fluoride group was significantly increased(P＜0.05);the expression levels of VDAC1,GRP75,and IP3R mRNA in the high-fluoride group were significantly increased(P＜0.01).(4)The level of cell apoptosis increased significantly after fluoride exposure,and the high-fluoride group was significantly higher than the control and low-fluoride groups(P＜0.01).(5)After fluoride exposure,the concentration of mitochondrial Ca2+in nerve cells increased significantly(P＜0.05),the mitochondrial membrane potential decreased(P＜0.01),and the degree of damage in the high-fluoride group was more obvious(P＜0.05).The results show that fluoride exposure impairs the morphological structure of primary neural cells,resulting in upregulation of Ca2+transfer pathway protein expression between the endoplasmic reticulum and mitochondria,mitochondrial Ca2+overload,mitochondrial damage,and increased levels of apoptosis.

BACKGROUND:Osteoarthritis is a chronic degenerative disease of the joints that can lead to disability.Its main pathological features are persistent inflammation and cartilage destruction.Triptolide has been used to treat a variety of chronic joint diseases.However,the mechanism of triptolide in the treatment of osteoarthritis has not been clarifiedOBJECTIVE:To identify the effective targets of triptolide in the treatment of osteoarthritis by network pharmacology,and to investigate the therapeutic effect of triptolide on osteoarthritis in the osteoarthritis model.METHODS:Network pharmacology was used to anticipate the potential targets and signaling pathways of triptolide in the treatment of osteoarthritis,and molecular docking technology was used to validate the core targets.A rat osteoarthritis model was established by anterior cruciate ligament transection.Eight weeks after modeling,the rats were administered with triptolide and sodium hyaluronate by intra-articular injection for 6 weeks.After 6 weeks of intervention,the pathological changes in rat knee joints were observed by hematoxylin-eosin staining and safranin O-fast green staining.The levels of inflammatory factors in rat serum were detected by enzyme-linked immunosorbent assay.The expression of aggrecan,type Ⅰ platelet-responsive protein-containing desmoglein metalloproteinase 5,type Ⅱ collagen and matrix metalloproteinase 13 proteins in rat articular cartilage was tested by immunohistochemical staining.RESULTS AND CONCLUSION:(1)The results of network pharmacology indicated that the target of triptolide may be related to the inhibition of the release of factors such as interleukin 6,tumor necrosis factor a,interleukin 1β,matrix metalloproteinase 9,and the over-activation of the nuclear factor-κB/JAK2-STAT3 signaling pathway.(2)Triptplide could reduce the degree of joint swelling in osteoarthritic rats;pathologically improve the articular cartilage and maintain the cartilage structure;decrease the serum levels of interleukin 6,tumor necrosis factor a,interleukin 1β,matrix metalloproteinase 9,and matrix metalloproteinase 3 in osteoarthritic rats;reduce the protein expression of matrix metalloproteinase 13 and type Ⅰ platelet-responsive protein-containing desmoglein metalloproteinase 5 in the articular cartilage;and increase the expression of type Ⅱ collagen and aggrecan in the cartilage,thereby achieving cartilage protection.

BACKGROUND:Acupuncture at Xinshu(BL 15)can significantly improve cardiac function and protect myocardial cells in acute myocardial ischemia,but the effect and mechanism of thread embedding treatment at Xinshu(BL 15)on cardiac function in acute myocardial ischemia are yet unclear.Nuclear factor κB activation often appears as an intranuclear translocation of the P65 isoform,and activation of the nuclear factor κB signaling pathway is marked by elevated P65 levels.OBJECTIVE:To explore the effects of thread embedding pretreatment at Xinshu(BL 15)on cardiac function and the expression levels of interleukin-10,tumor necrosis factor-α,P65 genes and proteins in rats with acute myocardial ischemia.METHODS:Thirty-two male Sprague-Dawley rats were randomly divided into a blank group,a model group,a Xinshu(BL 15)acupoint group,and a non-meridian/non-acupoint group using a random number table method,with eight rats in each group.Rat models of acute myocardial ischemia were established in the latter three groups.The Xinshu(BL 15)acupoint group had thread embedding at Xinshu(BL 15)for 14 days,followed by subcutaneous injection of isoproterenol hydrochloride into the back to establish an acute myocardial ischemia rat model.The non-meridian/non-acupoint group had local thread embedding for 14 days,and the rest procedures were the same as above.In the model group,Xinshu(BL 15)was only marked,and the rest procedures were the same as above.In the blank group,Xinshu(BL 15)was only marked,and then an equal amount of physiological saline was injected subcutaneously into the back.After 24 hours of modeling,electrocardiogram and cardiac ultrasound were performed.Abdominal aorta blood was extracted for detection of serum creatine kinase and creatine kinase isoenzyme levels using enzyme-linked immunosorbent assay.Subsequently,the rats were euthanized and samples were collected.Hematoxylin-eosin and TUNEL staining were used to observe the pathological changes of myocardial tissue and the apoptosis of myocardial cells.Real-time fluorescence quantitative PCR(RT-qPCR)and western blot were used to detect the mRNA and protein expression of tumor necrosis factor-α,interleukin-10,and P65 in myocardial tissue respectively.RESULTS AND CONCLUSION:(1)Electrocardiogram:Compared with the blank group,the model group,non-meridian/non-acupoint group,and Xinshu(BL 15)acupoint group had significantly elevated ST segment in lead Ⅱ of the electrocardiogram.(2)Cardiac ultrasound:Compared with the model group,the Left ventricular end-systolic dimension in the Xinshu(BL 15)acupoint group were significantly reduced(P＜0.05),while left ventricular ejection fraction and left ventricular fractional shortening rate were significantly increased(P＜0.05).(4)Serum creatine kinase and creatine kinase isoenzyme:Compared with the model group,the Xinshu(BL 15)acupoint group showed a significant decrease in serum creatine kinase and creatine kinase isoenzyme levels(P＜0.05).(4)Hematoxylin-eosin staining:Compared with the model group,the arrangement of myocardial fibers in the Xinshu(BL 15)acupoint group was basically neat,with less edema and a small amount of inflammatory cell infiltration.(5)TUNEL staining:Compared with the model group,the fluorescence intensity of myocardial cell apoptosis in the Xinshu(BL 15)acupoint group was significantly reduced,and its apoptosis rate was significantly reduced(P＜0.05).(6)RT-qPCR and western blot:Compared with the model group,the myocardial tissue interleukin-10 level in the Xinshu(BL 15)acupoint group was significantly increased(P＜0.05),while tumor necrosis factor-α and P65 levels were significantly decreased(P＜0.05).These findings indicate that thread embedding pretreatment at Xinshu(BL 15)can improve cardiac function in rats with acute myocardial ischemia,and its mechanism of action may be related to the inhibition of the activation of the nuclear factor-κB signaling pathway.

BACKGROUND:Sarcopenia is an age-related condition characterized by the loss of skeletal muscle mass,strength,and/or physical function.Currently,effective treatments for sarcopenia remain limited.A new therapeutic approach to improve symptoms and prognosis of sarcopenia patients clinically was important.OBJECTIVE:To explore the effects of canine adipose-derived mesenchymal stem cells and their exosomes on a dexamethasone-induced sarcopenia in mice.METHODS:Mesenchymal stem cells were isolated and cultured from canine adipose tissue,and identified and functionally evaluated through flow cytometry and differentiation assays for osteogenesis,adipogenesis,and chondrogenesis.Subsequently,exosomes from adipose-derived mesenchymal stem cells were extracted and characterized using transmission electron microscopy,western blot assay,and nanocoulter tracking analysis.In vitro,the effects of canine adipose-derived mesenchymal stem cells and their exosomes on myotube growth and the expression of muscle atrophy-related genes were investigated using dexamethasone-induced C2C12 myotube atrophy and aging C2C12 models.In vivo,a dexamethasone-induced mouse sarcopenia model was established and received intraperitoneal or intravenous injection of canine adipose-derived mesenchymal stem cells.Therapeutic efficacy was assessed through mouse rotarod performance,histopathological analysis,and muscle atrophy-related genes testing.RESULTS AND CONCLUSION:(1)The isolated canine adipose-derived mesenchymal stem cells highly expressed CD73,CD90,and CD105,and lowly expressed MHC-Ⅱ,CD14,CD19,CD34,and CD45,and successfully differentiated into osteoblasts,adipocytes,and chondrocytes in vitro.(2)The adipose-derived mesenchymal stem cells-derived exosomes met the identification criteria in terms of particle size,electron microscopy morphology,and positive expression of specific markers.(3)Compared to the dexamethasone-induced C2C12 atrophy group,treatment with adipose-derived mesenchymal stem cells and their exosomes promoted the recovery and growth of myotubes,inhibited the expression of muscle atrophy-related genes MuRF1 and Atrogin-1.(4)Compared to the aging C2C12 group,adipose-derived mesenchymal stem cells and their exosomes significantly enhanced the recovery and growth of aged muscle tubes in aging cells.(5)Compared to the control group,the rotarod time in dexamethasone-induced sarcopenia model mice was significantly decreased(P＜0.01).After 7 days(P＜0.01,P＜0.01)and 10 days(P＜0.01,P＜0.05)of adipose-derived mesenchymal stem cells treatment via intraperitoneal and intravenous injection,rotarod time was significantly increased,respectively.After 14 days,all treatment groups showed longer rotarod times than the model group,although with no significant differences between them.(6)Compared to the control group,the cross-sectional area of anterior tibial muscle in the model group was significantly reduced(P＜0.01),and it was significantly increased after intraperitoneal and intravenous administration of adipose-derived mesenchymal stem cells(P＜0.05,P＜0.01).(7)Compared to the model group,intraperitoneal and intravenous administration of adipose-derived mesenchymal stem cells significantly inhibited the mRNA expression of MuRF1 and Atrogin-1 genes(P＜0.01,P＜0.01,P＜0.01,P＜0.01).The results indicated that adipose-derived mesenchymal stem cells and their exosomes promoted recovery and growth of atrophic myotube cells by inhibiting the expression of muscle atrophy-related genes,and both intraperitoneal and intravenous administration of adipose-derived mesenchymal stem cells provided good therapeutic effects on sarcopenia in mice.

BACKGROUND:Neutrophil extracellular traps and activated platelets are involved in the invasion,metastasis,growth,and angiogenesis of lung cancer,and are closely related to the development and prognosis of lung cancer.OBJECTIVE:To review the mechanism of neutrophil extracellular traps and activated platelets in lung cancer and their application in diagnosis,prognosis,and treatment of lung cancer.METHODS:"Platelet activation,lung neoplasms,extracellular traps,treatment"for English search terms and"lung cancer,neutrophil-extracellular traps,platelet activation,P-selectin,treatment"for Chinese search terms were searched in PubMed and CNKI databases.After reading the title and abstract of the literature,according to the inclusion and exclusion criteria,63 articles with high relevance were finally included.RESULTS AND CONCLUSION:(1)Formation of neutrophil extracellular traps and platelet activation were induced by lung tumor.(2)Neutrophil extracellular traps and activated platelets jointly promote the proliferation,growth and metastasis of lung cancer.(3)Neutrophil extracellular traps can be used as a novel biomarker for the diagnosis,prognosis and progression of lung cancer.(4)Targeting neutrophil extracellular traps and activating platelets can be used as potential therapies for lung cancer.

BACKGROUND:Studies have confirmed that Pterocarya hupehensis skan total flavonoids(PHSTF)can improve the level of collagen-induced arthritis in rats,but there is still a lack of research on the regulation of Wnt/β-catenin signaling pathway in fibroblast-like synoviocytes and its effect on related cell functions.OBJECTIVE:To investigate the effect and mechanism of PHSTF on lipopolysaccharide-induced proliferation,migration and apoptosis of fibroblast-like synoviocytes based on the Wnt/β-catenin signaling pathwayMETHODS:Fibroblast-like synoviocytes were divided into control group,lipopolysaccharide group,lipopolysaccharide+low-,medium-,and high-dose PHSTF groups(10,20,and 40 μg/mL),lipopolysaccharide+Wnt pathway inhibitor DKK1 group,and lipopolysaccharide+Wnt pathway inhibitor DKK1+high-dose PHSTF group(40 μg/mL).The cell counting kit-8 method was used to detect the effect of PHSTF on the viability of fibroblast-like synoviocytes,and the final drug concentration and time were screened.Flow cytometry was used to detect the apoptosis of fibroblast-like synoviocytes.Cell scratch assay,EDU staining and cell cloning assay were used to detect the migration and proliferation of fibroblast-like synoviocytes.Western blot assay was used to detect the protein expression levels of Wnt3a,β-catenin,tumorigenic genes,matrix metalloproteinase 2,matrix metalloproteinase 9,Bax and Bcl-2 in fibroblast-like synoviocytes.RESULTS AND CONCLUSION:(1)Compared with the control group,the cell viability decreased significantly when the concentration of PHSTF was＞40 μg/mL(P＜0.01).Therefore,the drug concentration of≤40 μg/mL was selected for subsequent experiments.(2)Compared with the lipopolysaccharide group,the wound healing rate,cell clone formation rate and the number of EDU-positive cells in the low-,medium-and high-dose PHSTF groups were significantly reduced,while the apoptosis rate was significantly increased(P＜0.05-0.01).(3)Western blot results showed that compared with the lipopolysaccharide group,low-,medium-and high-dose PHSTF significantly inhibited cellular Wnt3a,β-catenin,cellular tumorigenic genes,matrix metalloproteinase 2,matrix metalloproteinase 9,and Bcl-2 protein expression,and promoted the expression of Bax protein(P＜0.01).(4)Compared with the DKK1 group,the combination of DKK1 and high-dose PHSTF significantly inhibited the protein expression of Wnt3a,β-catenin,matrix metalloproteinase 2,matrix metalloproteinase 9 and Bcl-2 protein expression and promoted the protein expression of Bax(P＜0.01).To conclude,PHSTF may inhibit the proliferation and migration of fibroblast-like synoviocytes and promote apoptosis by inhibiting the Wnt/β-catenin signaling pathway.

BACKGROUND:Abutment screw loosening is one of the most common mechanical complications in implant restoration.Mechanical wear,as a potential cause of thread loosening,warrants attention due to its impact on mechanical performance and long-term stability.However,studies on the mechanical effects of thread wear in abutment screws remain limited,and no definitive conclusions have been reached.OBJECTIVE:To investigate the effect of different degrees of mechanical wear on the spatial stress distribution of the Morse taper connection implant system,with a view to providing a theoretical basis for the clinical assessment of the long-term stability of dental implants.METHODS:Three-dimensional finite element models of Morse taper implants with central screw thread wear levels of 0,0.1,1,10,and 100 μm were established using SolidWorks software,and simulation analysis with Ansys Workbench software was performed.The implant models were inserted into artificial bone blocks(simulating type Ⅱ bone,with a cortical bone thickness of 2 mm on the outer layer and cancellous bone inside).An alternating load of 300 N in the buccolingual direction was applied at the centroid of the abutment(forming an angle of 30° with the long axis of the implant).The von Mises stress,principal stress,displacement,and fatigue life of the abutment,central screw,implant,and bone tissue in the five groups of models were analyzed.RESULTS AND CONCLUSION:(1)As the degree of mechanical wear on the central screw thread increased,the von Mises stress,principal stress,and strain in the implant and abutment also increased.The stress in the model was concentrated at the top of the implant,at the shoulder level of the implant,at the neck of the abutment,and at the bottom edge of the abutment.(2)Under moderate wear conditions(≥ 10 μm),the fatigue life of the implant system decreased by 30％,and the maximum von Mises stress of the central screw decreased by 37％,with the stress still primarily concentrated at the transition area between the head and the body of the central screw.(3)Under significant wear conditions(≥ 100 μm),the von Mises stress of the central screw decreased by 98％,with the stress concentrated at the screw head,and the fatigue life of the implant system decreased by 63％.Therefore,when the wear level of the central screw thread reaches ≥ 10 μm,the risk of screw loosening is significantly increased,and the fatigue life of the implant system is markedly reduced,warranting clinical attention.