BACKGROUND:The long-term effect of All-on-4 implant fixed denture is closely related to biomechanics.Its occlusion design affects the stress distribution of every part of the restoration.However,there is limited and inconclusive biomechanical research on All-on-4 implant fixed denture both domestically and internationally so far.OBJECTIVE:To analyze the effect of different occlusal contacts on the stress distribution of mandibular All-on-4 implant fixed denture.METHODS:A model of mandibular All-on-4 implant fixed denture was established.By changing the loading force,direction,and position,10 loading conditions were set up to simulate centric occlusion,laterotrusive occlusion,and protrusive occlusion.The stress distribution and maximum stress values of every part of the model in different loading conditions were analyzed and compared among each group of models by loading different tooth positions to simulate different occlusal contact types.RESULTS AND CONCLUSION:(1)The stress distribution cloud diagrams of each group of models were basically similar.The stress of the implant was mainly concentrated at the implant neck.The stress of the surrounding bone tissue was mainly concentrated around the implant neck,and the stress of the cortical bone was significantly higher than that of the cancellous bone.The stress of the abutment was mainly concentrated at the connection between the abutment and the implant and the abutment and the upper restoration.The stress of the titanium bracket in the upper restoration was mainly concentrated at the connection between the abutment and the titanium bracket,and the stress of the resin surface in the upper restoration was mainly concentrated on each loading point.(2)In simulating centric occlusion,the maximum stress value of the implant significantly increased when the cantilever was not loaded.It indicates that the mandibular All-on-4 implant fixed denture can have occlusal contact in the distal cantilever during centric occlusion.(3)In simulating laterotrusive occlusion,the maximum stress values of every part of the model significantly increased when simulating canine-guided occlusion.The maximum stress value of the simulated laterotrusive balanced occlusion was slightly lower than that of the simulated group functional occlusion.It indicates that group functional occlusion can be selected in the permanent prosthesis after osseointegration and laterotrusive balanced occlusion can be selected in the provisional restoration of mandibular All-on-4 implant fixed denture.(4)In simulating protrusive occlusion,the maximum stress values of every part of the model significantly increase when only the front tooth is loaded.In simulating protrusive balanced occlusion,the maximum Von-Mises stress value is relatively small.It indicates that the protrusive occlusion of mandibular All-on-4 implant fixed denture can choose protrusive balanced occlusion.

Objective To discuss the short-term efficacy of endovascular recanalization for symptomatic non-acute internal carotid artery occlusion.Methods A total of 90 patients with symptomatic non-acute internal carotid artery occlusion,who were admitted to the Department of Neurology of Tianjin Municipal Teda Hospital of China from August 2017 to December 2021,were selected as the research objects.The patients were divided into study group(n=45)and control group(n=45).Percutaneous endovascular recanalization of internal carotid artery occlusion was performed for the patients of the study group,and standardized antiplatelet aggregation and anti-lipid therapy(including oral aspirin,clopidogrel bisulphate and atorvastatin)was adopted for the patients of the control group.The symptom recurrence rate at one year after treatment in both groups was analyzed.Results Of the 45 patients in the control group,4 were lost in touch,and 41 completed the one-year follow-up.Of the 45 patients in the study group,2 patients had failure of surgery,one patient had lost contact visit,and 42 completed the one-year follow-up.Postoperative intracranial hemorrhage occurred in 2 patients.After one year of follow-up,in the control group 26 patients(63.41％)developed recurrence of symptoms,presenting as transient ischemic attack(TIA,n=13,31.7％)and cerebral infarction(n=13,31.7％),and in the study group 8 patients(4.76％)developed recurrence of symptoms,presenting as TIA(n=6,14.3％)and cerebral infarction(n=2,4.8％);the incidence of cerebral infarction in the study group was strikingly lower than that in the control group,and the difference between the two groups was statistically significant(P＜0.05).In the patients with grade Ⅲ compensation,the recurrence rate of symptoms was remarkably decreased after endovascular recanalization of internal carotid artery occlusion,and the difference between the two groups was statistically significant(P＜0.05).However,in the patients with grade Ⅰ or grade Ⅱ compensation,although the recurrence rate of symptoms was decreased after endovascular recanalization of internal carotid artery occlusion,the difference between the two groups was not statistically significant(P＞0.05).Conclusion For the treatment of patients with symptomatic non-acute internal carotid artery occlusion,percutaneous endovascular recanalization of internal carotid artery occlusion is clinically safe,it can significantly decrease the recurrence rate of symptoms.

BACKGROUND:The long-term effect of All-on-4 implant fixed denture is closely related to biomechanics.Its occlusion design affects the stress distribution of every part of the restoration.However,there is limited and inconclusive biomechanical research on All-on-4 implant fixed denture both domestically and internationally so far.OBJECTIVE:To analyze the effect of different occlusal contacts on the stress distribution of mandibular All-on-4 implant fixed denture.METHODS:A model of mandibular All-on-4 implant fixed denture was established.By changing the loading force,direction,and position,10 loading conditions were set up to simulate centric occlusion,laterotrusive occlusion,and protrusive occlusion.The stress distribution and maximum stress values of every part of the model in different loading conditions were analyzed and compared among each group of models by loading different tooth positions to simulate different occlusal contact types.RESULTS AND CONCLUSION:(1)The stress distribution cloud diagrams of each group of models were basically similar.The stress of the implant was mainly concentrated at the implant neck.The stress of the surrounding bone tissue was mainly concentrated around the implant neck,and the stress of the cortical bone was significantly higher than that of the cancellous bone.The stress of the abutment was mainly concentrated at the connection between the abutment and the implant and the abutment and the upper restoration.The stress of the titanium bracket in the upper restoration was mainly concentrated at the connection between the abutment and the titanium bracket,and the stress of the resin surface in the upper restoration was mainly concentrated on each loading point.(2)In simulating centric occlusion,the maximum stress value of the implant significantly increased when the cantilever was not loaded.It indicates that the mandibular All-on-4 implant fixed denture can have occlusal contact in the distal cantilever during centric occlusion.(3)In simulating laterotrusive occlusion,the maximum stress values of every part of the model significantly increased when simulating canine-guided occlusion.The maximum stress value of the simulated laterotrusive balanced occlusion was slightly lower than that of the simulated group functional occlusion.It indicates that group functional occlusion can be selected in the permanent prosthesis after osseointegration and laterotrusive balanced occlusion can be selected in the provisional restoration of mandibular All-on-4 implant fixed denture.(4)In simulating protrusive occlusion,the maximum stress values of every part of the model significantly increase when only the front tooth is loaded.In simulating protrusive balanced occlusion,the maximum Von-Mises stress value is relatively small.It indicates that the protrusive occlusion of mandibular All-on-4 implant fixed denture can choose protrusive balanced occlusion.

Objective:To assess the predictive value of aspartate aminotransferase-to-alanine amino-transferase ratio (DRR) on overall survival of patients with pancreatic ductal adenocarcinoma (PDAC) who underwent radical pancreaticoduodenectomy.Methods:A retrospective analysis was performed on the clinical data of 137 patients who underwent radical pancreaticoduodenectomy and were diagnosed with PDAC postoperatively at the Chinese PLA General Hospital from January 2015 to December 2020. There were 97 male and 40 female patients, with an average age of (58±10) years old. The patients were grouped according to the optimal survival risk cutoff value of DRR, and the differences in key clinical and pathological indicators between the groups were compared. Kaplan-Meier method was used for survival analysis, and log-rank test was used for comparison of survival rates. Multivariate Cox analysis was performed to evaluate the prognostic factors affecting survival.Results:The 137 PDAC patients were divided into two groups based on the optimal cutoff value of DRR, namely 1.1: DRR≥1.1 was defined as the high-DRR group ( n=29), and DRR<1.1 was defined as the low-DRR group ( n=108). The cumulative survival rate of the low-DRR group was better than that of the high-DRR group, and the difference was statistically significant ( P=0.003). The results of the multivariate Cox regression analysis showed that DRR≥1.1 ( HR=2.485, 95% CI: 1.449-4.261, P=0.001), preoperative biliary drainage ( HR=1.845, 95% CI: 1.030-3.306, P=0.039), lymph node metastasis N2 stage ( HR=2.240, 95% CI: 1.123-4.470, P=0.022), high tumor differentiation ( HR=2.001, 95% CI: 1.279-3.129, P=0.002), and intravascular cancer emboli ( HR=2.240, 95% CI: 1.123-4.470, P=0.022) were risk factors for poor overall survival in PDAC patients who underwent radical pancreaticoduodenectomy. Conclusion:DRR has predictive value for overall survival after surgery in PDAC patients undergoing radical pancreatoduodenectomy. A DRR of 1.1 or greater is a risk factor for poor overall survival after surgery in PDAC patients.

Intraductal papillary mucinous neoplasm (IPMN) is one of the precancerous lesions of the pancreas. Currently there is controversial over the management and follow-up strategy of IPMN, including the timing of surgery. The core problem lies in the accurate preoperative assessment of the nature of the lesions and the risk of malignant transformation. Cumulation of high-quality evidence and development of efficient evaluation methods are vital for the establishment of standardized decision-making system and the improvement of clinical benefits to patients. This review aims to summarize the consensus and controversies on surgical evaluation standards in the latest guidelines and representative literatures, and to look forward to the development direction of IPMN diagnosis and treatment decisions in combination with the progress of related evaluation techniques.

Desmoplastic stroma of pancreatic ductal adenocarcinoma plays an important role in tumor progression and treatment resistance. Stroma-targeted therapies are therefore promising for clinical application and extensive related researches are undergoing. In this article, recent advances in stromal targeting strategies were reviewed from three perspectives: cancer-associated fibroblasts, extracellular matrix and angiogenesis, and an outlook for the future of this strategy was also provided.

Objective:To study the risk factors for early recurrence of patients undergoing radical pancreaticoduodenectomy (PD) for pancreatic ductal adenocarcinoma (PDAC) and construct a normogram model.Methods:Patients undergoing open radical PD for PDAC at Faculty of Hepato-Pancreato-Biliary Surgery, Chinese PLA General Hospital from January 2014 to December 2021 were retrospectively screened. A total of 213 patients were enrolled, including 145 males and 68 females, aged (58.4±9.8) years. Patients were divided into the early recurrence group ( n=59, recurrence within 6 months after surgery) and a control group ( n=154, no recurrence within 6 months after surgery). Using minimum absolute value convergence and selection operator regression (LASSO) and multi-factor logistic regression analysis, we screened out the best predictor of early recurrence after PD for PDAC, and then established a nomogram model. The effectiveness of the model was validated by receiver operating characteristic (ROC) curve, calibration curves, and decision analysis curves. Results:Multivariate logistic regression analysis showed that patients with obstructive jaundice, vascular invasion, massive intraoperative bleeding, high-risk tumors (poorly differentiated or undifferentiated), high carbohydrate antigen 19-9 to total bilirubin ratio, and high fibrinogen and neutrophil to lymphocyte ratio scores had a higher risk of early postoperative recurrence. Based on the indexes above, a nomogram prediction model was constructed. The area under the ROC curve was 0.797 (95% CI: 0.726-0.854). Validation of the calibration curve exhibited good concordance between the predicted probability and ideal probability, decision curve analysis showed that the net benefits of the groupings established according to the model were all greater than 0 within the high risk threshold of 0.08 to 1.00. Conclusion:The nomogram for predicting early recurrence after PD for PDAC has a good efficiency, which could be helpful to screen out the high-risk patients for adjuvant or neoadjuvant therapy.

Objective:To construct a predictive nomogram on postoperative overall survival (OS) in patients with pancreatic ductal adenocarcinoma (PDAC) after R 0 radical pancreaticoduodenectomy, and to evaluate its performance. Methods:The clinicopathological data of patients who underwent radical pancreaticoduodenectomy at the Faculty of Hepato-Pancreato-Biliary Surgery, Chinese PLA General Hospital from January 2014 to December 2019 for pathologically diagnosed PDAC were retrospectively collected and analyzed. There were 119 patients, with 85 males and 34 females, aged (58±11) years. Using multivariate Cox regression analysis (stepwise regression), a prediction nomogram was constructed. Concordance index (C-index), calibration curve, and time-dependent receiver operating characteristic (ROC) curve were applied to evaluate the predictive performance.Results:The 1-, 2-, and 3-year cumulative survival rates of these 119 patients were 67.2%, 35.0%, and 24.8%, respectively. High-grade tumors (poorly differentiated and undifferentiated), vascular carcinoma embolus, systemic immune inflammatory index <279.4×10 9/L, prognostic nutritional index <40.5, alanine aminotransferase-to-aspartate aminotransferase ratio>1.1, total bilirubin>258.5 μmol/L and plasma fibrinogen>3.43 g/L were independent risk factors for poor OS for PDAC patients after radical pancreaticoduodenectomy (all P<0.05). These indicators, together with age >63 years, constituted the regression formula for prediction with a C-index=0.74. The areas under the curve of ROC for the nomogram on predicting survival were 0.795, 0.803, and 0.836 at 1, 2, and 3-year respectively, and only slight deviations were observed on the calibration curves from the standard 45° line, suggesting that the survival prediction of the model in this dataset fitted well with the actual survival status. Conclusion:The predictive nomogram on OS in patients after R 0 radical pancreaticoduodenectomy based on the clinicopathological characteristics of PDAC was internally validated to have a good predictive performance on OS. The nomogram can help to optimize prognostic risk stratification and treatment decisions for this subgroup of patients. This prediction model needs to be further verified and improved by using large-scale cohort studies.

Objective:To study the differences in preoperative examination indexes between pancreatic head cancer and distal bile duct cancer, and to establish a preliminary prediction model to provide reference for clinical decision-making.Methods:Retrospective analysis was conducted on 243 consecutive patients who underwent open radical pancreaticoduodenectomy from January 1, 2015 to December 31, 2019 at the Chinese PLA General Hospital. There were 177 males and 66 females, aged (58.9±8.9) years old. Based on postoperative pathological results, these 243 patients were divided into the pancreatic head cancer group ( n=113) and the distal bile duct cancer group ( n=130). The clinical data of the two groups were collected. Minimum absolute value convergence and selection operator regression were used to screen the best predictors of pancreatic head cancer. The rms package was used to construct the nomogram model, and k-fold cross was used for internal validation. Results:Seven best predictive indexes are selected: age, rate of weight loss, main pancreatic duct diameter, neutrophil/lymphocyte, DTR (DBil/TBil), carcinoembryonic antigen and CA125. Based on these indexes, a nomogram prediction model was constructed with the C-index of 0.868 after k-fold cross-validation, indicating that discrimination of the model to be acceptable. Validation using calibration curve exhibited good concordance between the predicted probability with the ideal probability ( P=0.728). Conclusion:The nomogram prediction model established in this study effectively predicted patients with pancreatic head cancer, and helped preoperatively to differentiate pancreatic head cancer from distal cholangiocarcinoma.

Objective:To study the risk factors of positive surgical margins in patients with advanced hilar cholangiocarcinoma (HCCA) undergoing curative-intent resection with the aim to provide references for clinical decision-making.Methods:The clinical pathological data of 126 patients with advanced HCCA who underwent curative-intent resection at the Chinese PLA General Hospital from January 2011 to December 2014 was retrospective analyzed. There were 78 males and 48 females, with an average age of 55 years. The patients were divided into two groups: the resection margin positive group (positive for residual tumor at any surgical margin, n=29) and the negative resection margin group ( n=97). Multivariate logistic regression analysis, in reference to the results of univariate analysis, was applied to the relevant variables to study independent risk factors of positive resection margin. Receiver operating characteristic (ROC) curves were drawn to evaluate the independent and joint predictive values of the relevant indicators. Results:Univariate analysis showed vascular involvement, tumor diameter volume ≥20.94 cm 3, plasma fibrinogen ≥3.36 g/L, and DRR≤0.61 were associated with positive resection margins (all P<0.05). A history of cholecystectomy was potentially associated with positive resection margins ( P<0.1). These variables were included in the multivariate logistic regression analysis which showed vascular involvement ( OR=4.134, 95% CI: 1.545-11.060, P=0.005), tumor size ≥ 20.94 cm 3 ( OR=2.926, 95% CI: 1.107-7.733, P=0.030) and DRR≤0.61 ( OR=3.170, 95% CI: 1.126-8.928, P=0.029) were independent risk factors of positive margins after curative resection in patients with advanced HCCA. ROC curve analysis was used to evaluate the impact of the combination of the above variables in predicting positive surgical margins. Sensitivity and specificity were calculated to be 86.2% and 65.7% respectively, and the area under the curve was 0.771. Conclusion:Vascular involvement, tumor size ≥20.94 cm 3 and DRR≤0.61 were independent risk factors of positive surfical margins in patients with advanced HCCA undergoing curative-intent resection. The combination of the above predictive indicators provided some references for treatment decisions.