1.The clinical significance of Th17 cell heterogeneity in myelodysplastic neoplasms
Yichen WANG ; Wenguang ZHOU ; Yanwen YAN ; Fang YI ; Lingsha QIN ; Wei LI ; Yuquan LI ; Xiangzong ZENG
Tianjin Medical Journal 2025;53(9):942-946
Objective To investigate the proportion of Th17 cells,Th1-like Th17 cells and FoxP3+Th17 cells in bone marrow of patients with myelodysplastic syndrome(MDS),the expression of interleukin-17A(IL-17A)in bone marrow supernatant and its clinical significance.Methods Forty MDS patients(MDS group)and 18 patients with nutritional anemia(control group)were selected.MDS patients were classified into the low blast(MDS-LB)group(19 cases)and the increased blast(MDS-IB)group(21 cases,including 11 cases of type IB1 and 10 cases of type IB2)based on morphological definition.The MDS patients were scored according to the revised International Prognostic Scoring System(IPSS-R),with 18 cases in the low-risk group(≤4.5)and 22 cases in the high-risk group(>4.5).Flow cytometry was used to detect the proportion of Th17 cells,Th1-like Th17 cells and FoxP3+Th17 cells in bone marrow of the MDS group and the control group.Enzyme-linked immunosorbent assay(ELISA)was used to detect the level of IL-17A in bone marrow supernatant of the above samples.Results The proportion of Th17 cells and the level of IL-17A were higher in patients of the MDS group than those in the control group(P<0.05).According to the median expression level of IL-17A,the MDS group was divided into the low-expression group(<13.71 ng/L,20 cases)and the high-expression group(≥13.71 ng/L,20 cases).Compared with the low-expression group,there were higher proportion of patients with blast cells<5%and low-risk patients(P<0.05)in the high-expression group.Compared with the IL-17A low-expression group,the IL-17A high-expression group had a higher proportion of patients with blast cells<5%and relatively low-risk patients(P<0.05).Compared with the low-risk patients,high-risk patients had a lower proportion of Th17 cells,IL-17A levels and Th1-like Th17 cells,and a higher proportion of FoxP3+Th17 cells(P<0.05).Compared with the MDS-LB group,the MDS-IB group had a lower proportion of Th17 cells,IL-17A levels and Th1-like Th17 cells,and a higher proportion of FoxP3+Th17 cells(P<0.05).Conclusion The proportion of Th17 cells and the level of IL-17A are significantly increased in MDS patients.The decreased proportion of Th1-like Th17 cells and the increased proportion of FoxP3+Th17 cells may be related to the increased proportion of blast cells and higher risk stratification in patients.
2.The clinical significance of Th17 cell heterogeneity in myelodysplastic neoplasms
Yichen WANG ; Wenguang ZHOU ; Yanwen YAN ; Fang YI ; Lingsha QIN ; Wei LI ; Yuquan LI ; Xiangzong ZENG
Tianjin Medical Journal 2025;53(9):942-946
Objective To investigate the proportion of Th17 cells,Th1-like Th17 cells and FoxP3+Th17 cells in bone marrow of patients with myelodysplastic syndrome(MDS),the expression of interleukin-17A(IL-17A)in bone marrow supernatant and its clinical significance.Methods Forty MDS patients(MDS group)and 18 patients with nutritional anemia(control group)were selected.MDS patients were classified into the low blast(MDS-LB)group(19 cases)and the increased blast(MDS-IB)group(21 cases,including 11 cases of type IB1 and 10 cases of type IB2)based on morphological definition.The MDS patients were scored according to the revised International Prognostic Scoring System(IPSS-R),with 18 cases in the low-risk group(≤4.5)and 22 cases in the high-risk group(>4.5).Flow cytometry was used to detect the proportion of Th17 cells,Th1-like Th17 cells and FoxP3+Th17 cells in bone marrow of the MDS group and the control group.Enzyme-linked immunosorbent assay(ELISA)was used to detect the level of IL-17A in bone marrow supernatant of the above samples.Results The proportion of Th17 cells and the level of IL-17A were higher in patients of the MDS group than those in the control group(P<0.05).According to the median expression level of IL-17A,the MDS group was divided into the low-expression group(<13.71 ng/L,20 cases)and the high-expression group(≥13.71 ng/L,20 cases).Compared with the low-expression group,there were higher proportion of patients with blast cells<5%and low-risk patients(P<0.05)in the high-expression group.Compared with the IL-17A low-expression group,the IL-17A high-expression group had a higher proportion of patients with blast cells<5%and relatively low-risk patients(P<0.05).Compared with the low-risk patients,high-risk patients had a lower proportion of Th17 cells,IL-17A levels and Th1-like Th17 cells,and a higher proportion of FoxP3+Th17 cells(P<0.05).Compared with the MDS-LB group,the MDS-IB group had a lower proportion of Th17 cells,IL-17A levels and Th1-like Th17 cells,and a higher proportion of FoxP3+Th17 cells(P<0.05).Conclusion The proportion of Th17 cells and the level of IL-17A are significantly increased in MDS patients.The decreased proportion of Th1-like Th17 cells and the increased proportion of FoxP3+Th17 cells may be related to the increased proportion of blast cells and higher risk stratification in patients.
3.Exploration on the Effects of Dahuang Lingxian Prescription on Cholestatic Liver Fibrosis Rats Based on the Bile Duct Reaction Associated with Liver Progenitor Cells
Yanping LUO ; Yuan YU ; Jun FU ; Huiyi WEI ; Jiaoan PANG ; Guiyuan YE ; Meng LIU ; Yichen WANG
Chinese Journal of Information on Traditional Chinese Medicine 2025;32(10):87-93
Objective To investigate the effects and mechanism of Dahuang Lingxian Prescription on bile duct reaction of cholestatic liver fibrosis rats caused by bile duct ligation.Methods A total of 40 SD rats were randomly divided into blank group,model group,ursodeoxycholic acid group and Dahuang Lingxian Prescription group,with 10 rats in each group.Except for the blank group,the remaining groups of rats underwent bile duct ligation surgery to establish a cholestatic liver fibrosis model.After surgery,the ursodeoxycholic acid group was given ursodeoxycholic acid solution by gavage,Dahuang Lingxian Prescription group was given Dahuang Lingxian Prescription solution by gavage,and the blank group and model group were given equal volume of normal saline by gavage,once a day for 3 consecutive weeks.The activities of serum AST,ALT,ALP,GGT and the contents of TBIL,TBA were tetected,the morphology of liver tissue was observed by HE staining,and the liver fibrosis was observed by Masson staining,immunohistochromic staining and Western blot were used to detect the expressions of CK19,CK7,EpCAM and SOX9 proteins.Results Compared with the blank group,the liver surface of the model group rats was rough,with a harder texture and obvious graininess,HE staining showed damage to the liver lobule structure,forming pseudo lobules,a large number of bile duct hyperplasia and inflammatory cell infiltration,and a significant increase in collagen fiber deposition(P<0.01);the activities of serum AST,ALT,ALP,GGT,as well as the contents of TBIL and TBA significantly increased(P<0.01);the positive expressions of CK19,CK7 and EpCAM in liver tissue significantly increased(P<0.01),and the protein expressions of CK19,CK7,EpCAM and SOX9 significantly increased(P<0.01).Compared with the model group,the appearance and texture of the liver of the rats in the ursodeoxycholic acid group and Dahuang Lingxian Prescription group were relatively softer,the lobular structure was less damaged,the inflammatory cells infiltration was less,the collagen fiber deposition was significantly reduced(P<0.01),the activities of serum AST,ALT,ALP,GGT,and the contents of TBIL and TBA were significantly decreased(P<0.01);the expressions of TBA and TBIL were significantly decreased(P<0.01),the positive expressions of CK19,CK7 and EpCAM significantly decreased(P<0.01),and the protein expression of CK19,CK7,EpCAM and SOX9 significantly decreased(P<0.01).Conclusion Dahuang Lingxian Prescription can inhibit the bile duct reaction associated with liver progenitor cells,decrease the expression of CK19,CK7,EpCAM and SOX9,and thus improve the cholestatic liver fibrosis of rats induced by bile duct ligation.
4.Impact of palliative care on medication use and medical utilization in patients with advanced cancer.
Dingyi CHEN ; Haoxin DU ; Yichen ZHANG ; Yanfei WANG ; Wei LIU ; Yuanyuan JIAO ; Luwen SHI ; Xiaodong GUAN ; Xinpu LU
Journal of Peking University(Health Sciences) 2025;57(5):996-1001
OBJECTIVE:
To evaluate the effect of palliative care on drug use, medical service utilization and medical expenditure of patients with advanced cancer.
METHODS:
A cohort of patients including pal-liative care and standard care was constructed using the medical records of the patients in Peking University Cancer Hospital from 2018 to 2020, and coarsened exact matching was used to match the two groups of patients. The average monthly opioid consumption, hospitalization rate, intensive care unit (ICU) rate and operation rate, and the average monthly total cost were selected to evaluate drug use, medical service utilization and medical expenditure. Chi-square test and Wilcoxon signed rank test were used to compare the differences between the two groups before and after exposure and the change in the palliative care group. The net impact of palliative care on the patients was calculated using the difference-in-differences analysis.
RESULTS:
In this study, 180 patients in the palliative care group and 3 101 patients in the stan-dard care group were finally included in the matching, and the matching effect of the two groups was good (L1 < 0.1). Before and after exposure, the average monthly opioid consumption in the palliative care group was significantly higher than that in the standard care group (Before exposure: 0.3 DDD/person-month vs. 0.1 DDD/person-month, P < 0.01; After exposure: 0.7 DDD/person-month vs. 0.1 DDD/person-month, P < 0.01; DDD refers to defined daily dose), palliative care significantly increased the average monthly opioid consumption in the patients (0.3 DDD/person-month, P < 0.01). The hospitalization rate (48.9% vs. 74.3%, P < 0.01) and operation rate (3.9% vs. 8.8%, P < 0.01) of the patients in palliative care group were significantly lower than those in standard care group, and the ICU rate became similar between the two groups (1.1% vs. 1.6%, P=0.634). Palliative care significantly reduced the patients ' hospitalization rate (-25.6%, P < 0.01), ICU rate (-4.9%, P < 0.01) and operation rate (-14.5%, P < 0.01). Before and after exposure, the average monthly total costs of pal-liative care group were slightly higher than those of standard care group (Before exposure: 20 092.3 yuan vs. 19 132.8 yuan, P=0.725; After exposure: 9 719.8 yuan vs. 8 818.8 yuan, P=0.165). Palliative care increased the average monthly total cost by 2 208.8 yuan, but it was not statistically significant (P=0.316).
CONCLUSION
Palliative care can increase the opioid consumption in advanced cancer patients, reduce the rates of hospitalization, ICU and surgery, but has no significant effect on medical expenditure.
Humans
;
Palliative Care/economics*
;
Neoplasms/drug therapy*
;
Analgesics, Opioid/economics*
;
Male
;
Female
;
Middle Aged
;
Aged
;
Hospitalization/economics*
;
Intensive Care Units/statistics & numerical data*
;
Health Expenditures/statistics & numerical data*
;
Adult
;
Drug Utilization/statistics & numerical data*
;
Patient Acceptance of Health Care/statistics & numerical data*
5.Exploration on the Effects of Dahuang Lingxian Prescription on Cholestatic Liver Fibrosis Rats Based on the Bile Duct Reaction Associated with Liver Progenitor Cells
Yanping LUO ; Yuan YU ; Jun FU ; Huiyi WEI ; Jiaoan PANG ; Guiyuan YE ; Meng LIU ; Yichen WANG
Chinese Journal of Information on Traditional Chinese Medicine 2025;32(10):87-93
Objective To investigate the effects and mechanism of Dahuang Lingxian Prescription on bile duct reaction of cholestatic liver fibrosis rats caused by bile duct ligation.Methods A total of 40 SD rats were randomly divided into blank group,model group,ursodeoxycholic acid group and Dahuang Lingxian Prescription group,with 10 rats in each group.Except for the blank group,the remaining groups of rats underwent bile duct ligation surgery to establish a cholestatic liver fibrosis model.After surgery,the ursodeoxycholic acid group was given ursodeoxycholic acid solution by gavage,Dahuang Lingxian Prescription group was given Dahuang Lingxian Prescription solution by gavage,and the blank group and model group were given equal volume of normal saline by gavage,once a day for 3 consecutive weeks.The activities of serum AST,ALT,ALP,GGT and the contents of TBIL,TBA were tetected,the morphology of liver tissue was observed by HE staining,and the liver fibrosis was observed by Masson staining,immunohistochromic staining and Western blot were used to detect the expressions of CK19,CK7,EpCAM and SOX9 proteins.Results Compared with the blank group,the liver surface of the model group rats was rough,with a harder texture and obvious graininess,HE staining showed damage to the liver lobule structure,forming pseudo lobules,a large number of bile duct hyperplasia and inflammatory cell infiltration,and a significant increase in collagen fiber deposition(P<0.01);the activities of serum AST,ALT,ALP,GGT,as well as the contents of TBIL and TBA significantly increased(P<0.01);the positive expressions of CK19,CK7 and EpCAM in liver tissue significantly increased(P<0.01),and the protein expressions of CK19,CK7,EpCAM and SOX9 significantly increased(P<0.01).Compared with the model group,the appearance and texture of the liver of the rats in the ursodeoxycholic acid group and Dahuang Lingxian Prescription group were relatively softer,the lobular structure was less damaged,the inflammatory cells infiltration was less,the collagen fiber deposition was significantly reduced(P<0.01),the activities of serum AST,ALT,ALP,GGT,and the contents of TBIL and TBA were significantly decreased(P<0.01);the expressions of TBA and TBIL were significantly decreased(P<0.01),the positive expressions of CK19,CK7 and EpCAM significantly decreased(P<0.01),and the protein expression of CK19,CK7,EpCAM and SOX9 significantly decreased(P<0.01).Conclusion Dahuang Lingxian Prescription can inhibit the bile duct reaction associated with liver progenitor cells,decrease the expression of CK19,CK7,EpCAM and SOX9,and thus improve the cholestatic liver fibrosis of rats induced by bile duct ligation.
6.Study on the perioperative coronary angiography results and surgical safety of 1 073 cases of multi-vessel CABG with left thoracic small incision
Yichen GONG ; Yunpeng LING ; Wei YANG ; Luyu MENG ; Zhongqi CUI ; Song WU ; Yuanhao FU ; Hui ZHENG
Chinese Journal of Thoracic and Cardiovascular Surgery 2025;41(6):359-365
Objective:To analyze the safety and efficacy of multi-vessel minimally invasive cardiac surgery-coronary artery bypass graft(MICS-CABG) through perioperative angiography results and complications.Methods:Clinical data of 1 073 patients who underwent multi-vessel MICS-CABG surgery at Peking University Third Hospital from December 2015 to June 2024 were collected using an ambispective cohort study. Among them, 745 were males(69.4%), with a median age of 65 years(58, 71), and a median ejection fraction of 0.66(0.56, 0.71). Double-vessel or triple-vessel lesions accounted for 932 cases(86.9%), while left main lesions were present in 449 cases(41.8%). The primary outcome was the evaluation of graft patency based on perioperative angiography or coronary artery computed tomography angiography results, while major cardiovascular adverse events during the perioperative period, surgical complications, and other surgical information were secondary outcomes. The clinical efficacy of multi-vessel MICS-CABG was evaluated.Results:In this study, the median number of grafts was 3, and complete revascularization was performed in 1 006 cases(93.8%); total arterial revascularization was performed in 308 cases(28.6%). Perioperative mortality was 11 cases(1.0%), and the main adverse cardiovascular and cerebrovascular events(MACCE) was 50 cases(4.8%). Three cases(0.3%) had poor wound healing, and 79 patients(7.4%) required transfusion. Postoperative coronary angiography was performed in 907 patients(84.5%) and coronary CTA was performed in 52 patients(4.8%), for an overall review rate of 89.4%(959/1073). The overall patency rate of the bridge vessel was 96.9%, and the patency rate of the left internal mammary artery was 98.2%.Conclusion:Multi-vessel MICS-CABG demonstrates excellent perioperative safety and is capable of achieving complete revascularization for the 3 regions of the heart. The quality of the anastomosis and the postoperative patency rate of the grafts is satisfactory.
7.Study on the perioperative coronary angiography results and surgical safety of 1 073 cases of multi-vessel CABG with left thoracic small incision
Yichen GONG ; Yunpeng LING ; Wei YANG ; Luyu MENG ; Zhongqi CUI ; Song WU ; Yuanhao FU ; Hui ZHENG
Chinese Journal of Thoracic and Cardiovascular Surgery 2025;41(6):359-365
Objective:To analyze the safety and efficacy of multi-vessel minimally invasive cardiac surgery-coronary artery bypass graft(MICS-CABG) through perioperative angiography results and complications.Methods:Clinical data of 1 073 patients who underwent multi-vessel MICS-CABG surgery at Peking University Third Hospital from December 2015 to June 2024 were collected using an ambispective cohort study. Among them, 745 were males(69.4%), with a median age of 65 years(58, 71), and a median ejection fraction of 0.66(0.56, 0.71). Double-vessel or triple-vessel lesions accounted for 932 cases(86.9%), while left main lesions were present in 449 cases(41.8%). The primary outcome was the evaluation of graft patency based on perioperative angiography or coronary artery computed tomography angiography results, while major cardiovascular adverse events during the perioperative period, surgical complications, and other surgical information were secondary outcomes. The clinical efficacy of multi-vessel MICS-CABG was evaluated.Results:In this study, the median number of grafts was 3, and complete revascularization was performed in 1 006 cases(93.8%); total arterial revascularization was performed in 308 cases(28.6%). Perioperative mortality was 11 cases(1.0%), and the main adverse cardiovascular and cerebrovascular events(MACCE) was 50 cases(4.8%). Three cases(0.3%) had poor wound healing, and 79 patients(7.4%) required transfusion. Postoperative coronary angiography was performed in 907 patients(84.5%) and coronary CTA was performed in 52 patients(4.8%), for an overall review rate of 89.4%(959/1073). The overall patency rate of the bridge vessel was 96.9%, and the patency rate of the left internal mammary artery was 98.2%.Conclusion:Multi-vessel MICS-CABG demonstrates excellent perioperative safety and is capable of achieving complete revascularization for the 3 regions of the heart. The quality of the anastomosis and the postoperative patency rate of the grafts is satisfactory.
8.Invasiveness assessment by CT quantitative and qualitative features of lung cancers manifesting ground-glass nodules in 555 patients: A retrospective cohort study
Yantao YANG ; Wei WANG ; Yichen YANG ; Biying WANG ; Huilian HU ; Ziqi JIANG ; Dezhong CAI ; Yaowu DUAN ; Jiezhi JIANG ; Jia LUO ; Guangqiang ZHAO ; Yunchao HUANG ; Lianhua YE
Chinese Journal of Clinical Thoracic and Cardiovascular Surgery 2024;31(01):51-58
Objective To explore the correlation between the quantitative and qualitative features of CT images and the invasiveness of pulmonary ground-glass nodules, providing reference value for preoperative planning of patients with ground-glass nodules. Methods The patients with ground-glass nodules who underwent surgical treatment and were diagnosed with pulmonary adenocarcinoma from September 2020 to July 2022 at the Third Affiliated Hospital of Kunming Medical University were collected. Based on the pathological diagnosis results, they were divided into two groups: a non-invasive adenocarcinoma group with in situ and minimally invasive adenocarcinoma, and an invasive adenocarcinoma group. Imaging features were collected, and a univariate logistic regression analysis was conducted on the clinical and imaging data of the patients. Variables with statistical difference were selected for multivariate logistic regression analysis to establish a predictive model of invasive adenocarcinoma based on independent risk factors. Finally, the sensitivity and specificity were calculated based on the Youden index. Results A total of 555 patients were collected. The were 310 patients in the non-invasive adenocarcinoma group, including 235 females and 75 males, with a meadian age of 49 (43, 58) years, and 245 patients in the invasive adenocarcinoma group, including 163 females and 82 males, with a meadian age of 53 (46, 61) years. The binary logistic regression analysis showed that the maximum diameter (OR=4.707, 95%CI 2.060 to 10.758), consolidation/tumor ratio (CTR, OR=1.027, 95%CI 1.011 to 1.043), maximum CT value (OR=1.025, 95%CI 1.004 to 1.047), mean CT value (OR=1.035, 95%CI 1.008 to 1.063), spiculation sign (OR=2.055, 95%CI 1.148 to 3.679), and vascular convergence sign (OR=2.508, 95%CI 1.345 to 4.676) were independent risk factors for the occurrence of invasive adenocarcinoma (P<0.05). Based on the independent predictive factors, a predictive model of invasive adenocarcinoma was constructed. The formula for the model prediction was: Logit(P)=–1.293+1.549×maximum diameter of lesion+0.026×CTR+0.025×maximum CT value+0.034×mean CT value+0.72×spiculation sign+0.919×vascular convergence sign. The area under the receiver operating characteristic curve of the model was 0.910 (95%CI 0.885 to 0.934), indicating that the model had good discrimination ability. The calibration curve showed that the predictive model had good calibration, and the decision analysis curve showed that the model had good clinical utility. Conclusion The predictive model combining quantitative and qualitative features of CT has a good predictive ability for the invasiveness of ground-glass nodules. Its predictive performance is higher than any single indicator.
9.Clinical and laboratory characteristics of 202 patients with cryoglobulinemia
Yichen MA ; Pengchang LI ; Jianhua HAN ; Wei JI ; Qian DI ; Wei SU
Chinese Journal of Laboratory Medicine 2024;47(1):78-85
Objective:To analyze the clinical and laboratory characteristics of patients with cryoglobulinemia.Methods:It is a cross-sectional study. The patients diagnosed with cryoglobulinemia in our hospital were enrolled from July 2017 to March 2023. The baseline information of patients, included age, gender, qualitative, and quantitative results of serum cryoglobulins, initial clinical manifestations, etiology, serum complement 3 and 4, and the renal pathological manifestations. The clinical and laboratory characteristics of patients with different types of cryoglobulinemia were analyzed.Results:There were 62 patients (30.7%) with type Ⅰ cryoglobulinemia, 58 patients (28.7%) with type Ⅱ cryoglobulinemia, and 82 patients (40.6%) with type Ⅲ cryoglobulinemia enrolled in this study. Among these patients, 56 of primary cryoglobulinemia, 76 of autoimmune diseases, 29 of tumor-related diseases, and 52 of infectious diseases were observed. Clinical symptoms related to skin lesions (124 cases, 61.4%) and kidney damage (87 cases, 43.1%) were the most common initial clinical manifestations and arthralgia/arthritis (50 cases, 24.8%), peripheral neuropathy (33 cases, 16.3%), fatigue (28 cases, 13.9%), fever (23 cases, 11.4%) were also observed in some patients. The clinical symptoms varied in different types of cryoglobulinemia. 29.0% patients (18/62) with type Ⅰ had fatigue, which was higher than those with type Ⅱ (10.3%, 6/58) and type Ⅲ (4.9%, 4/82) ( P<0.05); Kidney damage occurred in 56.9% (33/58) patients with type Ⅱ and 52.4% (43/82) patients with type Ⅲ, which was higher than that in type Ⅰ patients (17.7%, 11/62) ( P<0.05); Only 4 patients (4.9%, 4/82) with type Ⅲ had peripheral neuropathy, which was lower than those with type Ⅰ (17.7%, 11/62) and type Ⅱ (31.0%, 18/58) ( P<0.05). The quantity of cryoglobulins in patients with type Ⅲ cryoglobulinemia [122 (82, 177) mg/L] was significantly lower than that in patients with type Ⅰ [695(229, 3 499) mg/L] ( P<0.001) and type Ⅱ cryoglobulinemia [350 (107, 1 874) mg/L] ( P<0.001). Complement 4 decreased in 49.0% (99/202) of patients and complement 3 decreased in 42.6% (86/202) of patients. Membranoproliferative glomerulonephritis (36.0%, 9/25) and endocapillary proliferative glomerulonephritis (32.0%, 8/25) were the main renal pathological manifestations of cryoglobulin nephropathy. Conclusions:The most common clinical manifestations of cryoglobulinemia are skin and kidney damage. The clinical manifestations of patients with cryoglobulinemia vary in different types of cryoglobulins. Serum complement decreases in nearly half of cryoglobulinemia patients.
10.Investigation on the retentive force and fatigue property of different designed polyetheretherketone clasps
Yichen LUO ; Lin QIU ; Mingzhu GENG ; Wei ZHANG
STOMATOLOGY 2024;44(5):369-374
Objective By investigating the retention and fatigue performance of polyetheretherketone(PEEK)clasps with increased proportions of clasp arm engaging the undercut,an innovative method to improve PEEK clasps'performance was proposed and verified.Methods Three groups of PEEK clasps(n=10/group)with the terminal 1/3,2/3 and whole of their retentive arms engaging the 0.75 mm undercut were designed and fabricated respectively along with a group of cobalt-chrome clasps(n=10)with their terminal 1/3 of retentive arms engaging the 0.25 mm undercut.Retentive forces were recorded initially and every 1 500 cycles for a total of 15 000 in-sertion and removal fatigue cycles.Optical scanning and software analysis were applied to evaluate the deformation of the clasps by root mean square(RMS)after fatigue test.The inner surface morphology of clasps'arms was observed by scanning electron microscopy.Re-sults PEEK clasps with the whole of their retentive arms engaging the undercut exhibited highest mean retentive force(9.24±1.78)Namong other PEKK clasps,which was slightly lower than that of cobalt-chrome clasps(11.88±2.05)N.The retentive force of each group turned out to be reduced after fatigue cycles and cobalt-chrome clasps showed the greatest reduction(38.38%).The RMS of the PEEK clasps groups were of no statistical difference(P=0.111)and were lower than that of cobalt-chrome clasps(105.47±10.82)μm.Evidence of surface abrasion was observed on all groups of clasps especially on the section that engaged the undercut.Conclusion Increasing the proportion of PEEK clasp arm engaging the undercut effectively improved the retentive force and satisfied clinical re-quirements after fatigue cycles.PEEK clasps exhibited greater retention stability than cobalt-chrome clasps.It is feasible to improve the performance of PEEK clasps by increasing the proportion of clasp arm engaging the undercut.

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