1.Analysis of the current situation of poor vision and wearing of glasses among junior high school students in Xi'an City
Hui GAO ; Jiaqi WANG ; Zhirong LIU ; Jiateng WANG ; Lu YE
International Eye Science 2026;26(1):174-178
AIM:To investigate the prevalence of visual impairment and its correction status among junior high school students in Xi'an, so as to provide evidence for the development of targeted myopia prevention and control strategies.METHODS: A stratified cluster sampling design was adopted. From March to May 2025, students in grades 7-9 were recruited from three schools in Xi'an, Shaanxi Province, China: Dongfang Middle School, the Middle School Attached to Xi'an University of Technology, and the Xingqing Campus of the High School Affiliated to Xi'an Jiaotong University. In total, 3 974 students were invited, including 1 726 in grade 7, 1 206 in grade 8, and 1 042 in grade 9. The visual acuity was measured monocularly using a 5 m standard logarithmic visual acuity chart, with the fellow eye occluded; the line corresponding to the smallest optotype that could be correctly identified was recorded as the visual acuity value. Non-cycloplegic autorefraction was performed with a desktop autorefractor to obtain spherical equivalent(SE)values for refractive error screening.RESULTS: This study initially included 3 974 students, of whom 32 did not participate in the vision test, resulting in 3 942 students being included in the final analysis. Among them, 3 067(77.80%)were identified with poor vision. The prevalence of myopia was 81.47%(1 746)in males and 87.55%(1 575)in females(P<0.01). A stratified analysis by grade showed myopia rates of 81.72%(1 386)in junior grade one, 84.47%(1 017)in junior grade two, and 88.10%(918)in junior grade three, demonstrating a significant upward trend with increasing grade level(χ2=19.8484, P<0.01). Among the 3 321 myopic students, 2 287 adopted corrective measures. The rates of full correction, under-correction, and non-correction among all myopic students were 48.15%(1 599), 20.71%(688), and 31.14%(1 034), respectively. The rate of non-correction was significantly higher in male students than in females(32.70% vs 29.40%, χ2=4.2222, P<0.05).CONCLUSION: The findings indicate a high prevalence of visual impairment among junior high school students in Xi'an, coupled with suboptimal spectacle-wearing and full-correction rates. There is an urgent need for collaborative efforts across society, schools, and families to implement effective interventions to slow the onset and progression of myopia in this population.
2.Research progress on the relationship between early life obesogen exposure and childhood obesity
GAO Lei ; YE Zhen ; WANG Wei ; ZHAO Dong ; XU Peiwei ; ZHANG Ronghua
Journal of Preventive Medicine 2026;38(1):48-54
Childhood obesity has become a global public health issue. Current research indicates that early life obesogen exposure has emerged as a significant risk factor for childhood obesity. While obesogens have been confirmed to influence the development and progression of childhood obesity through mechanisms such as endocrine disruption and epigenetic programming, controversies remain regarding the establishment of causal relationships, assessment of combined exposures, and validation of transgenerational effects in humans. In recent years, novel approaches including multi-omics technologies, exposome-based analysis, and multigenerational cohort studies have integrated dynamic biomarker monitoring with analyses of social-environmental interactions, offering new perspectives and methodologies for constructing a systematic "exposure-mechanism-outcome" research framework. This article reviews literature from PubMed and Web of Science up to August 2025 on the association between early life obesogen exposure and childhood obesity, summarizing evidence on the health effects of early life obesogen exposure, major exposure pathways and internal exposure assessment, interactions and amplifying effects of social and environmental factors, as well as the biological mechanisms underlying obesogen action. It further examines current research frontiers and challenges, aiming to provide a theoretical foundation for early prevention and precision intervention of childhood obesity.
3.Mechanism of Yishen Huoxue Tongqiao Formula in Improving Unilateral Vestibular Labyrinth Destruction by Regulating Metabolism-neuroplasticity
Yu TIAN ; Hui LENG ; Rupeng QU ; Xianglong HAO ; Aiping WANG ; Lei SHI ; Zhongyuan QU ; Ye DONG ; Xiande MA ; Yangling HUANG
Chinese Journal of Experimental Traditional Medical Formulae 2026;32(5):54-64
ObjectiveThis study aims to explore the mechanism by which Yishen Huoxue Tongqiao Formula improves metabolism-neuroplasticity and treats unilateral vestibular labyrinth destruction by regulating the metabolic balance of glutamate (Glu)/γ-aminobutyric acid (GABA). Methods48 Sprague-Dawley (SD) adult rats were randomly divided into the sham operation group, model group, Yishen Huoxue Tongqiao Formula groups with low, medium, and high doses (9.20, 18.39, 36.78 g·kg-1), and betahistine group (1.62 mg·kg-1). A unilateral vestibular labyrinth destruction (vestibular dysfunction) model was established by intratympanic injection of chloroform into the right ear, while the control group received intratympanic injection of normal saline. Drugs were administered once daily for seven consecutive days. During the period, behavioral tests were performed to evaluate the behaviors of rats after unilateral vestibular labyrinth destruction. Hematoxylin-eosin (HE) staining and Nissl staining were used to observe the neuronal morphology in the medial vestibular nucleus. Golgi staining was employed to assess the number of dendritic spines of neurons in the medial vestibular nucleus. Ultra-performance liquid chromatography-tandem mass spectrometry (LC-ESI-MS/MS) was utilized to detect Glu/GABA. Immunofluorescence and immunohistochemistry were used to detect the expressions of neuronal nuclei (NeuN), growth-associated protein 43 (GAP-43), and glial fibrillary acidic protein (GFAP). Western blot and real-time fluorescent quantitative polymerase chain reaction (Real-time PCR) were applied to determine the expressions of glutamate-immunoreactive (Glu-IR), GABA, GFAP, postsynaptic density protein 95 (PSD-95), and GAP-43. ResultsCompared with the sham operation group, the model group presented with head deviation, balance disorder, increased tail suspension score, nuclear consolidation of medial vestibular nerve neurons, and decreased Nissl bodies (P<0.01). The number of dendritic spines in neurons and NeuN-positive cells decreased. The content of Glu decreased. The content of GABA increased (Glu/GABA decreased). The expression of GAP-43 was down-regulated, and GFAP was up-regulated (P<0.05, P<0.01). The expressions of Glu-IR, PSD-95, and GAP-43 proteins, as well as Glu-IR mRNA decreased, while the expressions of GABA and GFAP proteins and mRNA increased (P<0.05, P<0.01). Compared with those in the model group, the head deviation, imbalanced behavior, and tail suspension scores in each treatment group decreased, with alleviated neuronal injury and recovered Nissl bodies (P<0.01). The number of dendritic spines of neurons increased, and the number of NeuN-positive cells rebounded. The content of Glu increased, and the content of GABA decreased (Glu/GABA increased). GFAP was down-regulated, and GAP-43 was up-regulated (P<0.05, P<0.01). The expressions of Glu-IR, PMD-95, and GAP-43 proteins, as well as Glu-IR mRNA increased, while the expressions of GABA and GFAP proteins and mRNA decreased. The effect was more significant in the high-dose group (P<0.01). ConclusionThe Yishen Huoxue Tongqiao Formula can alleviate vestibular dysfunction, and its mechanism may be associated with regulating the metabolic balance of Glu/GABA, mitigating neural damage, improving synaptic plasticity (promoting GAP-43 expression and inhibiting GFAP expression), and facilitating vestibular compensation.
4.Expert consensus on neoadjuvant PD-1 inhibitors for locally advanced oral squamous cell carcinoma (2026)
LI Jinsong ; LIAO Guiqing ; LI Longjiang ; ZHANG Chenping ; SHANG Chenping ; ZHANG Jie ; ZHONG Laiping ; LIU Bing ; CHEN Gang ; WEI Jianhua ; JI Tong ; LI Chunjie ; LIN Lisong ; REN Guoxin ; LI Yi ; SHANG Wei ; HAN Bing ; JIANG Canhua ; ZHANG Sheng ; SONG Ming ; LIU Xuekui ; WANG Anxun ; LIU Shuguang ; CHEN Zhanhong ; WANG Youyuan ; LIN Zhaoyu ; LI Haigang ; DUAN Xiaohui ; YE Ling ; ZHENG Jun ; WANG Jun ; LV Xiaozhi ; ZHU Lijun ; CAO Haotian
Journal of Prevention and Treatment for Stomatological Diseases 2026;34(2):105-118
Oral squamous cell carcinoma (OSCC) is a common head and neck malignancy. Approximately 50% to 60% of patients with OSCC are diagnosed at a locally advanced stage (clinical staging III-IVa). Even with comprehensive and sequential treatment primarily based on surgery, the 5-year overall survival rate remains below 50%, and patients often suffer from postoperative functional impairments such as difficulties with speaking and swallowing. Programmed death receptor-1 (PD-1) inhibitors are increasingly used in the neoadjuvant treatment of locally advanced OSCC and have shown encouraging efficacy. However, clinical practice still faces key challenges, including the definition of indications, optimization of combination regimens, and standards for efficacy evaluation. Based on the latest research advances worldwide and the clinical experience of the expert group, this expert consensus systematically evaluates the application of PD-1 inhibitors in the neoadjuvant treatment of locally advanced OSCC, covering combination strategies, treatment cycles and surgical timing, efficacy assessment, use of biomarkers, management of special populations and immune related adverse events, principles for immunotherapy rechallenge, and function preservation strategies. After multiple rounds of panel discussion and through anonymous voting using the Delphi method, the following consensus statements have been formulated: 1) Neoadjuvant therapy with PD-1 inhibitors can be used preoperatively in patients with locally advanced OSCC. The preferred regimen is a PD-1 inhibitor combined with platinum based chemotherapy, administered for 2-3 cycles. 2) During the efficacy evaluation of neoadjuvant therapy, radiographic assessment should follow the dual criteria of Response Evaluation Criteria in Solid Tumors (RECIST) version 1.1 and immune RECIST (iRECIST). After surgery, systematic pathological evaluation of both the primary lesion and regional lymph nodes is required. For combination chemotherapy regimens, PD-L1 expression and combined positive score need not be used as mandatory inclusion or exclusion criteria. 3) For special populations such as the elderly (≥ 70 years), individuals with stable HIV viral load, and carriers of chronic HBV/HCV, PD-1 inhibitors may be used cautiously under the guidance of a multidisciplinary team (MDT), with close monitoring for adverse events. 4) For patients with a poor response to neoadjuvant therapy, continuation of the original treatment regimen is not recommended; the subsequent treatment plan should be adjusted promptly after MDT assessment. Organ transplant recipients and patients with active autoimmune diseases are not recommended to receive neoadjuvant PD-1 inhibitor therapy due to the high risk of immune related activation. Rechallenge is generally not advised for patients who have experienced high risk immune related adverse events such as immune mediated myocarditis, neurotoxicity, or pneumonitis. 5) For patients with a good pathological response, individualized de escalation surgery and function preservation strategies can be explored. This consensus aims to promote the standardized, safe, and precise application of neoadjuvant PD-1 inhibitor strategies in the management of locally advanced OSCC patients.
5.Effect and Mechanisms of Ermiao Formula Analogs and Their Active Components in Treating Dampness-heat Type Gouty Arthritis: A Review
Xueping ZHAO ; Xinya ZHANG ; Le YANG ; Ye SUN ; Xin SUN ; Hui SUN ; Qimeng ZHANG ; Guangli YAN ; Xijun WANG
Chinese Journal of Experimental Traditional Medical Formulae 2026;32(6):276-285
Gouty arthritis (GA) is caused by monosodium urate(MSU) deposition due to purine metabolism disorders. In traditional Chinese medicine (TCM), it falls under the category of "dampness-heat Bi syndrome", with core pathogenesis involving dampness-heat accumulation and dysfunction of the spleen and kidney. The dampness-heat syndrome is the most common and the primary syndrome type during acute attacks. In Western medicine, GA is associated with purine metabolism imbalance and inflammation triggered by MSU crystals, involving pathways such as NOD-like receptor protein 3 (NLRP3) inflammasome activation and Toll-like receptor 2/4 (TLR2/4) signaling. Clinically, colchicine and similar drugs are commonly used to treat GA, although long-term use carries potential side effects. Ermiao Formula analogs originate from ancient prescriptions, including Ermiao, Sanmiao, and Simiao compound formulas. All contain Atractylodis Rhizoma and Phellodendri Chinensis Cortex. Ermiaowan follow a 1∶1 formulation ratio. Sanmiaowan add Cyathulae Radix. Simiaowan further incorporate Coicis Semen. These formulas are rich in active ingredients, including alkaloids, terpenoids, flavonoids, and sterols, and treat GA through multi-component, multi-pathway, and multi-target mechanisms. Ermiaosan primarily exerts anti-inflammatory effects by inhibiting pathways such as TLR4/nuclear factor kappa-B (NF-κB) or regulating immune responses to reduce the release of inflammatory mediators, while also suppressing xanthine dehydrogenase (XDH) and xanthine oxidase (XO) activity to decrease uric acid production. Sanmiaowan enhance uric acid-lowering and anti-inflammatory effects through the guiding herb Cyathulae Radix, while also protecting cartilage from damage. Simiaowan utilizes Coicis Semen to regulate intestinal flora, alleviate dampness-heat symptoms, and exert multi-pathway anti-inflammatory and uric acid-lowering effects. The active ingredients contribute differently to uric acid metabolism regulation, anti-inflammation, antioxidant activity, and bone repair, resulting in varying therapeutic effects due to differences in formula composition. In summary, formulas derived from Ermiaosan demonstrate significant efficacy in treating dampness-heat type GA. This review summarizes their research progress and mechanisms, providing a reference for clinical application, new drug development, and further studies.
6.Natural control and clearance of hepatitis B virus infection
Jianyu YE ; Bing WANG ; Leyan GU ; Yingting FAN ; Jieliang CHEN
Journal of Clinical Hepatology 2026;42(1):7-13
Hepatitis B virus (HBV) is a unique hepatotropic DNA virus that forms covalently closed circular DNA within the nucleus of hepatocytes and can partially integrate into the host genome, establishing the molecular basis for persistent viral infection. HBV infection and replication depends on multiple hepatocyte-enriched host factors and is modulated by the hepatic microenvironment. The host achieves natural control and clearance of HBV through various mechanisms, including cytolytic elimination mediated by cellular immunity such as cytotoxic T lymphocytes and natural killer cells, innate immunity and noncytolytic clearance driven by interferons and various cytokines, and antibody-mediated protection and clearance as part of humoral immune response. In addition, intracellular restriction factors and pathways, hepatocyte turnover through division and replacement, and changes in the hepatic microenvironment (such as the increase in matrix stiffness) collectively influence the efficiency and outcome of viral control and clearance. This article clarifies and elaborates on related mechanisms, so as to deepen the understanding of HBV chronicity, spontaneous resolution, and cure and provide a theoretical basis for optimizing clinical management and developing novel therapeutic strategies.
7.Thromboelastographic features of patients with primary liver cancer and their value in assessing coagulation function
Chunjuan YE ; Chun ZHANG ; Jialu LI ; Sinan LIU ; Zheng WANG
Journal of Clinical Hepatology 2026;42(1):111-116
ObjectiveTo investigate the clinical application value of thromboelastographic parameters in assessing coagulation function by analyzing the thromboelastographic features of patients with primary liver cancer (PLC), and to provide a basis for coagulation management and prognostic evaluation in liver cancer patients. MethodsA retrospective analysis was performed for 1 253 PLC patients who were admitted to The First Affiliated Hospital of Xi’an Jiaotong University from May 2015 to December 2022. According to the presence or absence of cirrhosis, the patients were divided into non-cirrhosis group with 262 patients and cirrhosis group with 991 patients, and according to the presence or absence of HBV infection, they were divided into HBV infection group with 1 055 patients and non-HBV infection group with 198 patients. The patients were stratified based on the severity of liver cirrhosis (Child-Pugh class and MELD score) and liver reserve function (indocyanine green retention rate at 15 minutes [ICGR15]), and thromboelastography was used to measure thromboelastographic parameters (reaction time [R], coagulation formation time [K], α-angle, maximum thrombosis amplitude [MA], and coagulation composite index [CI]) and conventional coagulation markers. The t-test was used for comparison of normally distributed continuous data between two groups; a one-way analysis of variance was used for comparison between multiple groups, and the least significant difference t-test was used for further comparison between two groups. The Mann-Whitney U test was used for comparison of non-normally distributed continuous data between two groups; the Kruskal-Wallis H test was used for comparison between multiple groups, and the Bonferroni correction method was used for further comparison between two groups. The chi-square test was used for comparison of categorical data between grouips, and the Spearman test was used for correlation analysis. ResultsAmong the 991 patients in the cirrhosis group, 826 had Child-Pugh class A (5 — 6 points), and 165 had Child-Pugh class B (7 — 9 points); 812 had an MELD score of <10, and 179 had an MELD score of ≥10; 679 had an ICGR15 of <10%, and 294 had an ICGR15 of ≥10%. Compared with the patients with Child-Pugh class A, the patients with Child-Pugh class B had a significantly longer K time and significant reductions in α-angle, MA, and CI (all P <0.001); compared with the MELD score <10 group, the MELD score ≥10 group had a significantly longer K time and significant reductions in α-angle, MA, and CI (all P<0.001); compared with the ICGR15 <10% group, the ICGR15 ≥10% group had a significantly longer K time and a significant reduction in MA (both P <0.001). Among the 1 253 patients, MA was strongly positively correlated with fibrinogen and platelet count (r=0.675 and 0.667, both P<0.001); The MA had a weak correlation with Child-Pugh score, MELD score, and ICGR15 (r=-0.112, -0.250, and -0.117, all P<0.001), while the K time,α-angle and CI were weakly correlated with the MELD score (r=0.222, -0.184, and -0.183, all P<0.001),R time was negatively correlated with ICGR15 (r=-0.080, P=0.005). The HBV infection group had significantly higher MA and CI than the non-HBV infection group (P<0.05). ConclusionThromboelastography can sensitively identify the hypocoagulable state associated with the progression of liver cirrhosis and the hypercoagulable tendency in HBV-related liver cancer, which provides an important reference for individualized anticoagulant therapy in clinical practice.
8.Effects of wogonin on joint inflammation in collagen-induced arthritis rats via the endoplasmic reticulum stress pathway
Yuru WANG ; Siyuan LI ; Ye XU ; Yumeng ZHANG ; Yang LIU ; Huiqin HAO
Chinese Journal of Tissue Engineering Research 2025;29(5):1026-1035
BACKGROUND:Rheumatoid arthritis is an inflammatory disease.Many studies have shown that wogonin has a good anti-inflammatory effect on rheumatoid arthritis,but its exact efficacy and specific mechanism of action remain to be clarified. OBJECTIVE:To investigate the mechanism of wogonin ameliorating joint inflammation by regulating endoplasmic reticulum stress pathway in rats with collagen-induced arthritis. METHODS:(1)At the animal level:Female Wistar rats were divided into healthy control group,arthritis model group and wogonin treatment group.Rat models of arthritis in the latter two groups were established by subcutaneous injection of bovine type Ⅱ collagen and adjuvant.In the wogonin group,wogonin was given by gavage for 28 consecutive days after modeling.During this period,the rats in each group were weighed,and arthritis score and ankle swelling were measured every 7 days.After the experiment,the pathological changes of the joint were observed,the mRNA and protein levels of endoplasmic reticulum stress pathway GRP78 and CHOP were detected by qRT-PCR,western blot,and immunohistochemistry.(2)At the cellular level,cell counting kit-8 was used to detect the cytotoxic effect of wogonin on fibroblast-like synoviocytes from rats with collagen-induced arthritis.The fibroblast-like synoviocytes induced by thapsigargin were treated with different concentrations of wogonin.The levels of interleukin-1β and tumor necrosis factor-α in the cell supernatant were detected by ELISA,and the intracellular reactive oxygen species in each group were determined by DCFH-DA probe method.The mRNA and protein levels of GRP78,IRE1α,XBP1s and CHOP were detected by qRT-PCR and western blot,respectively. RESULTS AND CONCLUSION:Compared with the healthy control group,arthritis index score and ankle swelling degree in the arthritis model group were increased(P<0.01),synovial hyperplasia,inflammatory cell infiltration,cartilage destruction and bone erosion were observed in pathological sections,and the mRNA and protein expressions of GRP78 and CHOP in the ankle were significantly increased(P<0.01),which were mainly located in synovial tissue and articular surface.Compared with the arthritis model group,the arthritis index score and ankle swelling degree in the wogonin treatment group were decreased(P<0.05),synovial hyperplasia and the number of inflammatory cells were decreased,cartilage destruction and bone erosion were alleviated,the mRNA and protein expression levels of GRP78 and CHOP in the ankle were decreased(P<0.05),particularly in synovial tissue and on the articular surface.There was no significant difference in body mass among the three groups(P>0.05).In the cell experiment,200 μmol/L wogonin significantly reduced the survival rate of fibroblast-like synoviocytes(P<0.01).Compared with the blank control group,the levels of interleukin-1β,tumor necrosis factor-α,content of reactive oxygen species,and mRNA and protein expression of GRP78,IRE1α,XBP1s,and CHOP in the thapsigargin group were significantly increased(P<0.05);compared with the thapsigargin group,50 and 100 μmol/L wogonin significantly reduced the levels of interleukin-1β and tumor necrosis factor-α in the cell supernatant(P<0.05,P<0.01),and 100 μmol/L wogonin significantly reduced the content of reactive oxygen species(P<0.01)and down-regulated the mRNA and protein expression levels of GRP78,IRE1α,XBP1s and CHOP(all P<0.05).These results suggest that wogonin can effectively alleviate joint inflammatory responses in rats with collagen-induced arthritis,and the endoplasmic reticulum stress pathway may be the key target of its intervention.
9.Mitophagy regulates bone metabolism
Hanmin ZHU ; Song WANG ; Wenlin XIAO ; Wenjing ZHANG ; Xi ZHOU ; Ye HE ; Wei LI
Chinese Journal of Tissue Engineering Research 2025;29(8):1676-1683
BACKGROUND:In recent years,numerous studies have shown that autophagy and mitophagy play an important role in the regulation of bone metabolism.Under non-physiological conditions,mitophagy breaks the balance of bone metabolism and triggers metabolism disorders,which affect osteoblasts,osteoclasts,osteocytes,chondrocytes,bone marrow mesenchymal stem cells,etc. OBJECTIVE:To summarize the mechanism of mitophagy in regulating bone metabolic diseases and its application in clinical treatment. METHODS:PubMed,Web of Science,CNKI,WanFang and VIP databases were searched by computer using the keywords of"mitophagy,bone metabolism,osteoblasts,osteoclasts,osteocytes,chondrocytes,bone marrow mesenchymal stem cells"in English and Chinese.The search time was from 2008 to 2023.According to the inclusion criteria,90 articles were finally included for review and analysis. RESULTS AND CONCLUSION:Mitophagy promotes the generation of osteoblasts through SIRT1,PINK1/Parkin,FOXO3 and PI3K signaling pathways,while inhibiting osteoclast function through PINK1/Parkin and SIRT1 signaling pathways.Mitophagy leads to bone loss by increasing calcium phosphate particles and tissue protein kinase K in bone tissue.Mitophagy improves the function of chondrocytes through PINK1/Parkin,PI3K/AKT/mTOR and AMPK signaling pathways.Modulation of mitophagy shows great potential in the treatment of bone diseases,but there are still some issues to be further explored,such as different stages of drug-activated mitophagy,and the regulatory mechanisms of different signaling pathways.
10.Finite element analysis of various root shield thicknesses in maxillary central incisor socket-shield technique
Guangneng CHEN ; Siyang LUO ; Mei WANG ; Bin YE ; Jiawen CHEN ; Yin LIU ; Yuwen ZUO ; Xianyu HE ; Jiajin SHEN ; Minxian MA
Chinese Journal of Tissue Engineering Research 2025;29(10):2052-2060
BACKGROUND:Socket-shield technique can effectively maintain labial soft and hard tissues,but the incidence of postoperative complications such as exposure and displacement of root shield is relatively high.It is speculated that the root shield may be exposed and displaced due to excessive load after long-term function of dental implants. OBJECTIVE:Through three-dimensional finite element analysis,we aim to study the influence of varying root shield thicknesses on the stress distribution,equivalent stress peaks,and displacement in the root shield,periodontal ligaments,implant,and surrounding alveolar bone under normal occlusal loading.We also attempt to analyze the correlation between the thickness of the root shield and occurrence of mechanical events such as root shield exposure,displacement,and fracture. METHODS:Cone-beam CT data of a patient who met the indication standard of socket-shield technique for maxillary central incisor were retrieved from database.Reverse engineering techniques were used to build models of the maxillary bone and root shield,while forward engineering was used to create models for the implant components based on their parameters.Models depicting various root shield thicknesses(0.5,1.0,1.5,and 2.0 mm)were created using Solidworks 2022 software.ANSYS Workbench 2021 software was then used to simulate and analyze the effects of varying root shield thicknesses on stress distribution,equivalent stress peaks,and displacement of the root shields,periodontal ligaments,implants,and surrounding alveolar bone under normal occlusion. RESULTS AND CONCLUSION:(1)In all root shield models,the stress was concentrated on the palatal cervical side,both sides of the edges and the lower edge of the labial side.As the thickness of the root shield increased,the equivalent stress peak and displacement showed a decreasing trend.The 0.5 mm thickness model produced a stress concentration of 176.20 MPa,which exceeded the yield strength(150 MPa)of tooth tissue.(2)The periodontal ligament stress in each group was concentrated in the neck margin and upper region.With the increase of root shield thickness,the equivalent stress peak and displacement of periodontal ligament showed a decreasing trend.(3)Implant stress in all models was concentrated in the neck of the implant and the joint of the implant-repair abutment,and the labial side was more concentrated than the palatal side.With the increase of root shield thickness,the equivalent stress peak of the implant in the model showed an increasing trend.(4)In each group of models,stress of cortical bone concentrated around the neck of the implant and the periphery of the root shield,and the labial side was more concentrated than the palatal side.With the increase of the thickness of the root shield,the equivalent stress peak around the root shield decreased;the peak value of the equivalent stress of the bone around the neck of the implant showed an increasing trend.In the model,the stress of cancellous bone was mainly concentrated around the neck of the lip of the implant,the top of the thread,the root tip and the lower margin of the root shield,and the labial side was more concentrated than the palatal side.With the increase of the thickness of the root shield,the peak value of the equivalent stress of the bone around the root shield in the model showed a decreasing trend.The minimum principal stress of cortical bone in each group of models was concentrated around the neck of the implant,exhibiting a fan-shaped distribution.As the thickness of the root shield increased,the minimum principal stress of cortical bone showed an increasing trend.(5)These results indicate that different thicknesses of the root shield have different biomechanical effects.The root shield with a thickness of 0.5 mm is easy to fracture.For patients with sufficient bone width,the root shield with a thickness of 2.0 mm is an option to reduce the risk of complications such as root shield exposure,fracture,and displacement.Meanwhile,it should be taken into account to protect the periodontal ligament in the preparation process,and rounding treatments ought to be carried out on both sides and the lower edge of the root shield.


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