1.Effect of Epimedium brevicornu Ethanol Extract on Aging of Castrated Rats by Intervening in Mesenchymal Adipose-derived Stem Cells
Zuyu MENG ; Haiquan LIU ; Shaozi LIN ; Mei WANG ; Yiyao ZHANG ; Fang LIU ; Menghan LI ; Hongling CHEN ; Jiajia QIN
Chinese Journal of Experimental Traditional Medical Formulae 2025;31(1):174-181
ObjectiveTo explore the mechanism by which the ethanol extract of Epimedium brevicornu (EEBM) intervenes in mesenchymal adipose-derived stem cells (ADSCs) to delay aging in castrated rats. MethodsForty-five 3-month-old SPF female SD rats were ovariectomized and randomly divided into model group, ADSCs treatment group, and ADSCs groups treated with low, medium, and high concentrations of EEBM (1, 50, 100 μg·L-1), referred to as the AE low, medium, and high concentration groups, with 9 rats in each group. After tail vein injection of 200 μL of the corresponding stem cell suspension, aging-related indicators including cyclin-dependent kinase inhibitor (p21), tumor suppressor gene (p53), interleukin-6 (IL-6), interleukin-8 (IL-8), superoxide dismutase (SOD), malondialdehyde (MDA), B-cell lymphoma-2 (Bcl-2), Bcl-2-associated X protein (Bax), cysteine-aspartic acid protease-3 (Caspase-3), and lipofuscin were measured using enzyme-linked immunosorbent assay (ELISA) and Western blot. ResultsCompared with the model group, the IL-6 content in the AE low, medium, and high concentration groups was significantly decreased (P<0.05). Lipofuscin, MDA, and IL-8 levels in the ADSCs treatment group and AE low, medium, and high concentration groups were significantly reduced (P<0.01), while SOD content was significantly increased (P<0.05, P<0.01). Compared with the ADSCs treatment group, lipofuscin and IL-8 levels in the AE low, medium, and high concentration groups were significantly reduced (P<0.05, P<0.01). The MDA content was significantly decreased in the AE medium concentration group (P<0.01). Compared with the model group, protein levels of p21, p53, Bax, and Caspase-3 in the ADSCs treatment group and AE low, medium, and high concentration groups were significantly reduced (P<0.05, P<0.01), while the Bcl-2 protein level was significantly increased (P<0.01). Compared with the ADSCs treatment group, protein levels of p21, p53, Bax, and Caspase-3 in the AE low, medium, and high concentration groups were significantly reduced (P<0.05, P<0.01), and the Bcl-2 protein level in the AE low concentration group was significantly increased (P<0.01). ConclusionThe results of this experiment show that EEBM-treated ADSCs or ADSCs may delay aging in castrated rats by inhibiting cell apoptosis, reducing cell cycle inhibitors and pro-inflammatory factors, enhancing antioxidant capacity, and reducing oxidative reactions. Moreover, EEBM-treated ADSCs demonstrate stronger anti-aging effects than ADSCs alone. This study provides experimental evidence supporting the clinical use of EEBM to intervene in ADSCs and delay aging.
2.Expert Consensus on Clinical Diseases Responding Specifically to Traditional Chinese Medicine: Atopic Dermatitis
Junfeng LIU ; Xiumei MO ; Mei MO ; Hongyi LI ; Ying LIN ; Xiaoxiao ZHANG ; Dacan CHEN
Chinese Journal of Experimental Traditional Medical Formulae 2025;31(1):244-252
Atopic dermatitis (AD) is a common pruritic and chronic inflammatory dermatosis in clinical practice and is one of the diseases responding specifically to traditional Chinese medicine (TCM). With the launch of biological agents and small molecule drugs and the development and implementation of guidelines of diagnosis and treatment, clinical pathways of treatment of moderate to severe AD, and consensus on the whole-process management of AD, the clinical efficacy of moderate to severe AD has been significantly improved. However, there are still many unmet clinical needs that require more effective methods to meet. In response to the Opinions of the CPC Central Committee and the State Council on Facilitating the Inheritance, Innovation, and Development of Traditional Chinese Medicine and the spirit of the National Conference on TCM, the China Association of Chinese Medicine organized more than 20 experts in TCM dermatology, Western medicine dermatology, interdisciplinary fields, and industries to discuss the difficulties and advantages of TCM in the treatment of AD. TCM treatment for AD can not only improve rash and relieve itching but also solve many concomitant syndromes. The abundant external treatment methods of TCM have advantages for different special populations and rash characteristics. The concept of treating disease before its onset in TCM is in line with the chronic disease management mode of prevention and treatment of atopic march and prevention of recurrence. In addition, TCM therapy can reduce the use of topical glucocorticoids and has good safety. Regarding the comorbidity of AD, equal emphasis on TCM and Western medicine and multidisciplinary joint treatment should be advocated to achieve maximum benefit for patients. The exchange of TCM and Western medicine has clarified the positioning and advantages of TCM intervention in AD, providing guidance for clinical and scientific research.
3.Simultaneous TAVI and McKeown for esophageal cancer with severe aortic regurgitation: A case report
Liang CHENG ; Lulu LIU ; Xin XIAO ; Lin LIN ; Mei YANG ; Jingxiu FAN ; Hai YU ; Longqi CHEN ; Yingqiang GUO ; Yong YUAN
Chinese Journal of Clinical Thoracic and Cardiovascular Surgery 2025;32(02):277-280
A 71-year-old male presented with esophageal cancer and severe aortic valve regurgitation. Treatment strategies for such patients are controversial. Considering the risks of cardiopulmonary bypass and potential esophageal cancer metastasis, we successfully performed transcatheter aortic valve implantation and minimally invasive three-incision thoracolaparoscopy combined with radical resection of esophageal cancer (McKeown) simultaneously in the elderly patient who did not require neoadjuvant treatment. This dual minimally invasive procedure took 6 hours and the patient recovered smoothly without any surgical complications.
4.Trends in disease burden due to childhood asthma from 1990 to 2021 and future projections in China
Chinese Journal of School Health 2025;46(4):573-578
Objective:
To investigate the trends in disease burden due to childhood asthma in China from 1990 to 2021 and to project the disease burden from 2022 to 2035, so as to provide insights into formulation of the control interventions for childhood asthma in China.
Methods:
The prevalent case, agestandard prevalence, disability-adjusted life years (DALYs) and agestandard DALYs rate of children with asthma at ages of 0 to 14 years and their 95% uncertainty interval (UI) in China from 1990 to 2021 were extracted from the Global Burden of Disease (GBD) database. The temporal trends in the disease burden of childhood asthma were evaluated with estimated annual percentage change (EAPC) and its 95% confidence interval (CI), and the disease burden due to asthma was projected among children at ages of 0 to 14 years in China using a Bayesian age-period-cohort (BAPC) model from 2022 to 2035.
Results:
There were 9.368 3 million (95%UI=6.410 7 million to 14.026 1 million) prevalent cases of asthma among children at ages of 0 to 14 years in China in 2021, contributing to 0.387 9 million (95%UI=0.216 1 million to 0.668 8 million) DALYs loss. The prevalent cases and DALYs of asthma decreased by 37.28% and 52.55% among children at ages of 0 to 14 years in China in 2021 compared with 1990, and the agestandardized prevalence [EAPC=-0.70%, 95%CI=-1.26% to -0.13%)] and DALY rates [EAPC=-1.71%, 95%CI=-2.32% to -1.10%)] also appeared a tendency towards a decline. From 1990 to 2021, the prevalent cases, prevalence, DALYs and DALYs rate of asthma were all higher among male children than among female children, and the disease burden of asthma was higher among children at ages of 5 to 9 years than at other age groups. BAPC model predicted a decline in both prevalent cases and DALYs of asthma among children at ages of 0 to 14 years in China from 2022 to 2035, with 6.759 6 million prevalent cases and DALYs of 0.228 4 million personyears in 2035, while the prevalence and DALYs rates were projected to rise to 5 143.35/105 and 173.75/105 in 2035.
Conclusions
Despite a reduction in the disease burden of asthma among children at ages of 0 to 14 years in China from 1990 to 2021, the prevalence remained high. The disease burden due to asthma is projected to appear a decline among children at ages of 0 to 14 years in China from 2022 to 2035; however, the prevalence and DALYs rates still rise. Intensified control measures and targeted interventions are required to reduce the disease burden of childhood asthma.
5.Objective characteristics of tongue manifestation in different stages of damp-heat syndrome in diabetic kidney disease
Zhaoxi DONG ; Yang SHI ; Jiaming SU ; Yaxuan WEN ; Zheyu XU ; Xinhui YU ; Jie MEI ; Fengyi CAI ; Xinyue ZANG ; Yan GUO ; Chengdong PENG ; Hongfang LIU
Journal of Beijing University of Traditional Chinese Medicine 2025;48(3):398-411
Objective:
To investigate the objective characteristics of tongue manifestation in different stages of damp-heat syndrome in diabetic kidney disease (DKD).
Methods:
A cross-sectional study enrolled 134 patients with DKD G3-5 stages who met the diagnostic criteria for damp-heat syndrome in DKD. The patients were treated at Dongzhimen Hospital, Beijing University of Chinese Medicine, from May 2023 to January 2024. The patients were divided into three groups: DKD G3, DKD G4, and DKD G5 stage, with 53, 33, and 48 patients in each group, respectively. Clinical general data (gender, age, and body mass index) and damp-heat syndrome scores were collected from the patients. The YZAI-02 traditional Chinese medicine (TCM) AI Tongue Image Acquisition Device was used to capture tongue images from these patients. The accompanying AI Open Platform for TCM Tongue Diagnosis of the device was used to analyze and extract tongue manifestation features, including objective data on tongue color, tongue quality, coating color, and coating texture. Clinical data and objective tongue manifestation characteristics were compared among patients with DKD G3-5 based on their DKD damp-heat syndrome status.
Results:
No statistically significant difference in gender or body mass index was observed among the three patient groups. The DKD G3 stage group had the highest age (P<0.05). The DKD G3 stage group had a lower score for symptoms of poor appetite and anorexia(P<0.05) than the DKD G5 group. No statistically significant difference was observed in damp-heat syndrome scores among the three groups. Compared with the DKD G5 stage group, the DKD G3 stage group showed a decreased proportion of pale color at the tip and edges of the tongue (P<0.05). The DKD G4 stage group exhibited an increased proportion of crimson at the root of the tongue, a decreased proportion of thick white tongue coating at the root, a decreased proportion of pale color at the tip and edges of the tongue, an increased hue value (indicating color tone) of the tongue color in the middle, an increased brightness value (indicating color lightness) of the tongue coating color in the middle, and an increased thickness of the tongue coating (P<0.05). No statistically significant difference was observed in other tongue color proportions, color chroma values, body characteristics, coating color proportions, coating color chroma values, and coating texture characteristics among the three groups.
Conclusion
Tongue features differ in different stages of DKD damp-heat syndrome in multiple dimensions, enabling the inference that during the DKD G5 stage, the degree of qi and blood deficiency in the kidneys, heart, lungs, liver, gallbladder, spleen, and stomach is prominent. Dampness is more likely to accumulate in the lower jiao, particularly in the kidneys, whereas heat evil in the spleen and stomach is the most severe. These insights provide novel ideas for the clinical treatment of DKD.
6.Identification of Alumen and Ammonium alum Based on XRD, FTIR, TG-DTA Combined with Chemometrics
Bin WANG ; Jingwei ZHOU ; Huangsheng ZHANG ; Jian FENG ; Hanxi LI ; Guorong MEI ; Jiaquan JIANG ; Hongping CHEN ; Fu WANG ; Yuan HU ; Youping LIU ; Shilin CHEN ; Lin CHEN
Chinese Journal of Experimental Traditional Medical Formulae 2025;31(13):178-186
ObjectiveTo establish the multi-technique characteristic profiles of Alumen by X-ray diffraction(XRD), Fourier-transform infrared spectroscopy(FTIR) and thermogravimetric-differential thermal analysis(TG-DTA), and to explore the spectral characteristics for rapid identification of Alumen and its potential adulterant, Ammonium alum. MethodsA total of 27 batches of Alumen samples from 8 production regions were collected for preliminary identification based on visual characteristics. The PDF standard cards of XRD were used to differentiate Alumen from A. alum, and the XRD characteristic profiles of Alumen were established, and then the common peaks were screened. Based on hierarchical clustering analysis(HCA) and orthogonal partial least squares-discriminant analysis(OPLS-DA), the characteristic information that could be used for identification of Alumen was selected with variable importance in the projection(VIP) value>1. FTIR characteristic profiles of Alumen were established, and key wavenumbers for identification were screened by HCA and OPLS-DA with VIP value>1. Meanwhile, the thermogravimetric differences between Alumen and A. alum were analyzed by TG-DTA, and the thermogravimetric traits that could be used for identification were screened. ResultsAlumen and A. alum could not be effectively distinguished by traits alone. However, by comparing the PDF standard cards of XRD, 15 batches of Alumen and 12 batches of A. alum could be distinguished. In the XRD profiles, 10 characteristic peaks were confirmed, corresponding to diffraction angles of 14.560°, 24.316°, 12.620°, 32.122°, 17.898°, 34.642°, 27.496°, 46.048°, 40.697° and 21.973°. In the FTIR profiles, 4 wavenumber ranges(399.193-403.050, 1 186.010-1 471.420, 1 801.190-2 620.790, 3 612.020-3 997.710 cm-1) and 12 characteristic wavenumbers(1 428.994, 1 430.922, 1 432.851, 1 434.779, 1 436.708, 1 438.636, 1 440.565, 1 442.493, 1 444.422, 1 446.350, 1 448.279, 1 450.207 cm-1) were identified. In the TG-DTA profiles, there were characteristic decomposition peaks of ammonium ion and mass reduction features near 555.34 ℃ for A. alum. These characteristics could serve as important criteria for distinguishing the authenticity of Alumen. ConclusionXRD, FTIR and TG-DTA can be used to rapidly detect Alumen and A. alum, and combined with the discriminant features selected through chemometrics, the rapid and accurate identification of Alumen and A. alum can be achieved. The research findings provide new approaches for the rapid identification of Alumen.
7.Process Optimization and Health Risk Assessment of Calcined Haematitum Based on QbD Concept
Yue YANG ; Jingwei ZHOU ; Jialiang ZOU ; Guorong MEI ; Yifan SHI ; Lei ZHONG ; Jiaojiao WANG ; Xuelian GAN ; Dewen ZENG ; Xin CHEN ; Lin CHEN ; Hongping CHEN ; Shilin CHEN ; Yuan HU ; Youping LIU
Chinese Journal of Experimental Traditional Medical Formulae 2025;31(13):187-196
ObjectiveTo investigate the processing technology of calcined Haematitum based on the concept of quality by design(QbD) and to assess its health risk. MethodsTaking whole iron content, Fe2+ dissolution content and looseness as critical quality attributes(CQAs), and calcination temperature, calcination time, spreading thickness and particle size as critical process parameters(CPPs) determined by the failure mode and effect analysis(FMEA), the processing technology of calcined Haematitum was optimized by orthogonal test combined with analytic hierarchy process-criteria importance through intercriteria correlation(AHP-CRITIC) hybrid weighting method. The contents of heavy metals and harmful elements were determined by inductively coupled plasma mass spectrometry, and the health risk assessment was carried out by daily exposure(EXP), target hazard quotient(THQ) and lifetime cancer risk(LCR), and the theoretical value of the maximum limit was deduced. ResultsThe optimal processing technology for calcined Haematitum was calcination at 650 ℃, calcination time of 1 h, particle size of 0.2-0.5 cm, spreading thickness of 1 cm, and vinegar quenching for 1 time[Haematitum-vinegar(10:3)]. The contents of 5 heavy metals and harmful elements in 13 batches of calcined Haematitum were all decreased with reductions of up to 5-fold. The cumulative THQ of 2 batches of samples was>1, while the cumulative THQ of all batches of Haematitum was>1. The LCR of As in 1 batches of Haematitum was 1×10-6-1×10-4, and the LCR of the rest was<1×10-6, and the LCRs of calcined Haematitum were all<1×10-6, indicating that the carcinogenic risk of calcined Haematitum was low, but special attention should still be paid to Haematitum medicinal materials. Preliminary theoretical values of the maximum limits of Cu, As, Cd, Pb and Hg were formulated as 1 014, 25, 17, 27, 7 mg·kg-1. ConclusionThe optimized processing technology of calcined Haematitum is stable and feasible, and the contents of heavy metals and harmful elements are reduced after processing. Preliminary theoretical values of the maximum limits of Cu, As, Cd, Pb and Hg are formulated to provide a scientific basis for the formulation of standards for the limits of harmful elements in Haematitum.
8.Clinical Diseases Responding Specially to TCM Treatment: Psoriasis
Liu LIU ; Xiaoying SUN ; Mei MO ; Yaqiong ZHOU ; Bin LI ; Xiaoxiao ZHANG ; Xin LI
Chinese Journal of Experimental Traditional Medical Formulae 2025;31(5):260-268
Psoriasis is a common chronic inflammatory systemic disease in dermatology. Its high prevalence, recurrence rate, and numerous comorbidities impose a significant physical and mental burden on patients. With the continuous advancement of modern medicine, the emergence of biological agents has improved clinical efficacy, making it possible to overcome psoriasis, in addition to classical treatments. However, in clinical practice, adverse reactions, drug resistance, recurrence rates, and immune drift cannot be ignored. Traditional Chinese medicine (TCM) has a history of thousands of years in treating psoriasis, demonstrating good efficacy, high safety, and a low recurrence rate, but a standardized management system is lacking. Therefore, the 25th Clinical Diseases Responding Specially to TCM Treatment Series (Psoriasis) Youth Salon, hosted by the Chinese Association of Chinese Medicine and organized by the Youth Committee of the Chinese Association of Chinese Medicine, invited 29 experts and scholars from TCM, Western medicine, and interdisciplinary fields to actively discuss the "Advantages, Challenges, and Clinical Transformation of TCM and Western Medicine in the Diagnosis and Treatment of Psoriasis". The experts at the meeting concluded that the advantages of TCM in the treatment of psoriasis are as follows. Firstly, in the TCM-led treatment plan, TCM's understanding of psoriasis follows the principle of combining the differentiation of disease and syndrome. This approach distinguishes the basic contradiction from the current main contradiction and enables a clear grasp of the dynamic process of psoriasis development. Based on the system of syndrome differentiation and treatment, TCM intervention is applied to address the current main contradiction, and the optimal TCM treatment plan is formulated by combining internal and external treatments. Adhering to the principle of "what is visible outside must be addressed inside", TCM can prevent and treat psoriasis comorbidities early by differentiating syndrome types. Secondly, in the integrated TCM and Western medicine treatment plan, the combination of both methods not only enhances efficacy but also reduces the adverse reactions of immunosuppressants and biological agents, lowering the recurrence rate. This conference provides a reference for the diagnosis and treatment of psoriasis using TCM and integrated TCM and Western medicine, opening up new ideas for clinical and basic research and guiding future research directions.
9.Mid-long term follow-up reports on head and neck rhabdomyosarcoma in children
Chao DUAN ; Sidou HE ; Shengcai WANG ; Mei JIN ; Wen ZHAO ; Xisi WANG ; Zhikai LIU ; Tong YU ; Lejian HE ; Xiaoman WANG ; Chunying CUI ; Xin NI ; Yan SU
Chinese Journal of Pediatrics 2025;63(1):62-69
Objective:To analyze the clinical characteristics of children with head and neck rhabdomyosarcoma (RMS) and to summarize the mid-long term efficacy of Beijing Children′s Hospital Rhabdomyosarcoma 2006 (BCH-RMS-2006) regimen and China Children′s Cancer Group Rhabdomyosarcoma 2016 (CCCG-RMS-2016) regimen.Methods:A retrospective cohort study. Clinical data of 137 children with newly diagnosed head and neck RMS at Beijing Children′s Hospital, Capital Medical University from March 2013 to December 2021 were collected. Clinical characteristic of patients at disease onset and the therapeutic effects of patients treated with the BCH-RMS-2006 and CCCG-RMS-2016 regimens were compared. The treatments and outcomes of patients with recurrence were also summarized. Survival analysis was performed by Kaplan-Meier method, and Log-Rank test was used for comparison of survival rates between groups.Results:Among 137 patients, there were 80 males (58.4%) and 57 females (41.6%), the age of disease onset was 59 (34, 97) months. The primary site in the orbital, non-orbital non-parameningeal, and parameningeal area were 10 (7.3%), 47 (34.3%), and 80 (58.4%), respectively. Of all patients, 32 cases (23.4%) were treated with the BCH-RMS-2006 regimen and 105 (76.6%) cases were treated with the CCCG-RMS-2016 regimen. The follow-up time for the whole patients was 46 (20, 72) months, and the 5-year progression free survival (PFS) and overall survival (OS) rates for the whole children were (60.4±4.4)% and (69.3±4.0)%, respectively. The 5-year OS rate was higher in the CCCG-RMS-2016 group than in BCH-RMS-2006 group ((73.0±4.5)% vs. (56.6±4.4)%, χ2=4.57, P=0.029). For the parameningeal group, the 5-year OS rate was higher in the CCCG-RMS-2016 group (61 cases) than in BCH-RMS-2006 group (19 cases) ((57.3±7.6)% vs. (32.7±11.8)%, χ2=4.64, P=0.031). For the group with meningeal invasion risk factors, the 5-year OS rate was higher in the CCCG-RMS-2016 group (54 cases) than in BCH-RMS-2006 group (15 cases) ((57.7±7.7)% vs. (30.0±12.3)%, χ2=4.76, P=0.029). Among the 10 cases of orbital RMS, there was no recurrence. In the non-orbital non-parameningeal RMS group (47 cases), there were 13 (27.6%) recurrences, after re-treatment, 7 cases survived. In the parameningeal RMS group (80 cases), there were 40 (50.0%) recurrences, with only 7 cases surviving after re-treatment. Conclusions:The overall prognosis for patients with orbital and non-orbital non-parameningeal RMS is good. However, children with parameningeal RMS have a high recurrence rate, and the effectiveness of re-treatment after recurrence is poor. Compared with the BCH-RMS-2006 regimen, the CCCG-RMS-2016 regimen can improve the treatment efficacy of RMS in the meningeal region.
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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