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.

BACKGROUND:Bone tissue remodeling is closely related to stress loading.Currently,there are few studies or guidelines on the relationship between bone and occlusal adjustment of implant prostheses and there is also a lack of scientific evidence. OBJECTIVE:To investigate the effects of different implant occlusal gaps on stress distribution,stress peak and displacement at the implant-bone interface under Ⅰ-Ⅳ bone conditions by a finite element method. METHODS:After scanning the equal-scale tooth model with an optical scanner,equal-scale models of the upper right first molar Straumann 4.8×8 mm BL RC implant and its related components was constructed using Solidworks 2022.Then,using Mimics,Geomagic,and Solidworks software,the maxillary and mandibular bone models of class Ⅰ-Ⅳ bones were established based on the bone classification proposed by ZARB and LEKHOLM in the literature,and the NORTON and TRISI bone density classification method.The models were assembled with the occlusal gaps of 0,20,40,60,80,and 100 μm for the restorations,and an additional set of homogeneous models without density ratio settings was constructed for comparison.After the above models were imported into Hypermesh for meshing,the material assignment,boundary constraints and parameter setting were performed for the finite element analysis.Finally,250 N was used as the loading force to simulate the maxillary and mandibular stress conditions.Stress distribution,peak stress and displacement of the implant-bone interface in each group of models were analyzed and compared. RESULTS AND CONCLUSION:Under the same loading conditions,the stresses in the implant restorations were evenly distributed with the occlusal contact points.When the occlusal gap reached 80 and 100 μm,stress interruptions occurred in the implant crowns under class Ⅰ bone and class Ⅱ,Ⅲ and Ⅳ bones,respectively.The displacement of the implant-bone interface was mainly concentrated in the cortical bone region around the implant and transmitted down the long axis of the implant to the cancellous bone region at the bottom.With the changes of class Ⅰ-Ⅳ jaw bones,the displacement and Von Mises stress in the cortical bone region increased in all groups,and were greater than those in the cancellous bone region.The Von Mises stress in the cancellous bone region was similar to that in the cortical bone region except that it showed a downward trend from class Ⅱ bone.However,when the occlusal gap increased,the stress and displacement peak values in the cortical bone and the cancellous bone showed a decreasing trend.The stress of the implant-bone interface was between 20 MPa and 60 MPa when the occlusal gap was 0-40 μm for class Ⅱ-Ⅳ bones and 60 μm for class Ⅳ bone,and the stress of the other groups was less than 20 MPa.The Von Mises stress was mainly concentrated in the neck of the implant,and the peak value of von Mises stress in class Ⅱ-Ⅳ bones with the occlusal gap of 20 μm was higher than that(144.10 MPa)in class Ⅰ bone with the occlusal gap of 0 μm.In the homogeneous model with different elastic moduli,the distribution of stress and displacement was more uniform than that in the heterogeneous model and the occlusal space should increase with the decrease of jaw bone density in clinical practice.To conclude,from the perspective of biomechanics,the alveolar bone should be taken into account in the occlusal adjustment of implant denture.An occlusal gap of 20-40 μm between a single dental implant and a natural tooth in the opposite jaw is a relatively suitable solution for occlusal adjustment under different bone conditions.However,due to the particularity of finite element analysis method,it needs to be further studied in combination with clinical practice.

Radiation-related caries is a common complication following head and neck tumor radiotherapy. It is a rapidly progressing and widespread destructive disease of tooth tissue after radiotherapy, which greatly affects the life quality of patients after radiotherapy. This article elucidates research progress in the pathogenic mechanisms, diagnosis and caries assessment, treatment, as well as prevention strategies for radiation-related caries, aiming to provide references for clinical prevention and treatment of radiation-related caries.

Objective To form the expert consensus on the limb management of patients with transvenous temporary cardiac pacing,standardize the limb management of patients with transvenous temporary cardiac pacing,and reduce complications related to the limb.Methods Using evidence-based methods,the evidence in this field was searched,evaluated and summarized,and relevant recommendations and research conclusions were extracted and classified by the level of evidence quality,and then the first draft of the consensus was formed.From December 2023 to January 2024,through 2 rounds of expert consultation and 4 rounds of expert meetings,the content was adjusted and the consensus was reached.Results Totally 16 experts participated in the consultation.The positive coefficient is 100%;the authoritative coefficient is 0.847 and 0.836;the average value of each index is more than＞3.8;the coefficient of variation is less than 0.21.The Kendall's harmony coefficient of the 2 rounds of expert consultation is 0.372 and 0.314,respectively,which were statistically significant.The consensus covers the preoperative,intraoperative and postoperative on limb management of patients with transvenous temporary cardiac pacing.Totally 11 themes were involved,including the preoperative preparation,position and catheter fixation in operation,position and catheter fixation in postoperative,activity,turn and transfer,duty shift on limb,nursing care after withdrawal of the catheter,prevention of deep vein thrombosis of the operative limb and prevent infection.Conclusion The consensus is highly scientific,and it is helpful to standardize the limb management of patients with transvenous temporary cardiac pacing.

Objective:To investigate the ethics and existing problems of experimental animals in medical experiments and experimental teaching, and to formulate countermeasures so that animal ethics and animal welfare can be truly reflected in medical experiments.Methods:In this study, a "Basic Function Experiment Center Animal Experiment Questionnaire" with 25 questions was formulated from three aspects: the ethical cognition of experimental animals, whether animal experiments are ethical or not, how to view the problems of animal ethics and experimental teaching and the cognition of virtual simulation experiment teaching. Questionnaire was sent to Hubei University of Medicine to investigate the international students of Batch 2017 (5-year program), undergraduates of Batch 2017 (5-year program) and nursing students of Batch 2018 (4-year program) as well as teachers, researchers and employees of laboratory animal center (all with bachelor degree or above). The survey results were expressed as percentage.Results:The recovery rate of the questionnaire in this study was 98.04%(2 451/2 500), among which the practitioners, teachers and researchers in the laboratory animal center clearly understood the ethics of experimental animals, but there was a widespread phenomenon of lagging ethics among the students. For example, 16.24% (398/2 451) students had not received animal experiment ethics education and training, 29.46% (722/2 451) were not clear about animal protection laws and regulations, 7.14% (175/2 451) thought animal experiments were immoral; 29.54% (724/2 451) had vague cognition of animal welfare and ethical knowledge; 25.91% (635/2 451) were not familiar with the operation steps; 9.38% (230/2 451) were indifferent to the extra treatment of animals due to operation errors, 7.83% (192/2 451) chose to give up the experiment in the treatment of animals after massive bleeding, only 5.43% (133/2 451) chose to continue the experiment after timely hemostasis and infusion, and 9.26% (227/2 451) chose to do operations unrelated to the experiment. After the experiment, 2.28% (56/2 451) chose to kill the animals by bloodletting, only 5.51% (135/2 451) chose excessive anesthesia euthanasia, and 1.96% (48/2 451) chose to kill the animals by cervical dislocation and violence. Only 15.79% (387/2 451) chose to remember the dead animal for 2 minutes. Only 32.56%(798/2 451) of the respondents understood virtual simulation experiment, 34.92% (856/2 451) of the respondents thought that virtual simulation experiment or experimental teaching video could be used to replace the existing live animal experiment, 77.56% (1 901/2 451) believed that the construction of virtual simulation laboratory should be strengthened.Conclusion:It is imperative to strengthen the education of students' ethics of experimental animals, which is conducive to the establishment of correct ethics of experimental animals for medical students, so that the "3R" principle and animal welfare can be truly implemented in experimental teaching and scientific research experiments.

Objective:To compare the efficacy of intraluminal microwave ablation with radiofrequency ablation in the treatment of varicose veins of the lower extremities.Methods:The clinical data of 520 patients (522 affected limbs) who underwent lower extremity varicose vein surgery at the Department of Vascular Surgery of the First Affiliated Hospital of Anhui Medical University from Jun 2021 to Sep 2022 were collected. Patients were divided into endovenous microwave ablation group (EMWA group, n = 201) and radiofrequency ablation group (RFA group, n = 321). Follow-up was performed at 1 week, 1 , 6 and 12 months after surgery. The primary efficacy endpoint was the occlusion rate of the treated segment vein, the primary safety endpoint was the incidence of surgery-related and/or device-related complications, and the secondary endpoints were the venous clinical severity score (VCSS) and chronic venous insufficiency quality of life questionnaire (CIVIQ) scores at follow-up. Results:The technique success rate and the occlusion rate of the affected segment vein was 100% in both groups evaluated one week after surgery; Six and 12 months after surgery, the occlusion rate in the RFA group was 98.9%, and that in the EMWA group was 99.3% and respectively 97.8%, 97.2% ,without statically significant difference.During the follow-up period, there were no cases of reoperation due to vein recanalization. no serious events such as deep vein thrombosis, pulmonary embolism or death occurred in either group. The incidence of adverse events (induration, ecchymosis, skin burn, incision infection, limb numbness, hematoma, thrombotic superficial phlebitis, endovenous heat induced thrombosis, etc.) in both groups was compared, and the difference was not statistically significant. VCSS and CIVIQ scores improved significantly in both groups at 1 ,6 and 12 months after treatment, and the difference was statistically significant(all P < 0.01). Conclusion:EMWA and RFA have the advantages of simple operation, good clinical efficacy and high degree of improvement in quality of life.

Objective:To investigate the repair effect of amphiregulin (Areg) on injured lung tissue in mice with acute respiratory distress syndrome (ARDS) and its underlying mechanism.Methods:The ARDS mouse model was made by tracheal infusion of lipopolysaccharide (LPS), and bronchoalveolar lavage fluid (BALF) was extracted for 7 consecutive days. Adult male C57BL/6 mice were randomly (random number) divided into 5 groups ( n=4 per group): (1) Control group; (2) Areg group: mice were treated intraperitoneally (i.p.) with recombinant Areg; (3) LPS+PBS group; (4) LPS+Areg group; and (5) LPS+Anti-Areg group; mice were instilled with LPS, then were injected i.p. with PBS, Areg or Areg neutralization antibody (Anti-Areg) 30 min later. Lung tissue and BALF were extracted at day 1, 3, 5 and 7 after ARDS. HE staining was used to evaluate the pathological changes of lung tissues. The total protein content in BALF was detected by BCA method, and the concentrations of tumor necrosis factor-α (TNF-α), interleukin-6 (IL-6), IL-1β and immunoglobulin M (IgM) were determined by ELISA method. The phosphorylated levels of epidermal growth factor receptor (EGFR) and expressions of proliferating cell nuclear antigen (PCNA) and surface proteins-C (SP-C) were tested by Western blot. The immunofluorescence was used to detect the co-expression of PCNA and SP-C in lung tissues. One-way analysis of variance was used to compare the mean values of normally distributed measurement data between groups. Comparisons between groups were performed using the least significant difference t-test. Results:Compared with that at before modeling [(51.05±2.47) pg/mL], Areg concentrations were increased significantly at day 1 [(71.97±6.51) pg/mL; P<0.01] and day 3 [(147.58±7.56) pg/mL, P<0.01] in the BALF after ARDS. At day 1 after ARDS, there were significant interstitial edema, neutrophil infiltration and alveolar collapse in the LPS+PBS group and LPS+Areg group. Compared with the LPS+PBS group at day 3, 5 and 7, the pathological changes of lung tissues were notably improved in the LPS+Areg group, while were more serious in the LPS+Anti-Areg group. Compared with the control group, the LPS+PBS group had higher levels of neutrophil number, total protein, IgM, TNF-α, IL-1β, and IL-6. However, Areg treatment significantly reduced the levels of these indicators. Moreover, the expressions of PCNA (1.34±0.10), SP-C (1.48±0.10) and p-EGFR (0.92±0.032) in the LPS+Areg group were significantly up-regulated compared with those in the LPS+PBS group (0.88±0.03, 1.06±0.15, and 0.68±0.03, all P<0.01). And compared with the LPS+PBS group, PCNA and SP-C double positive cells were significantly increased in the LPS+Areg group, but decreased in the LPS+Anti-Areg group. Conclusions:Areg enhances the proliferation of alveolar typeⅡ epithelial cells by activating EGFR pathway, therefore promotes the repair of lung tissues during ARDS development.

Objective:To evaluate the role of epidermal growth factor (EGF) in repair of lung tissues in mice with acute respiratory distress syndrome (ARDS).Methods:Fifty SPF male C57BL/6 mice, aged 6-8 weeks, weighing 21-23 g, were divided into 5 groups ( n=10 each) using a random number table method: control group (group C), EGF group, LPS+ PBS group, LPS+ EGF group and AG1478+ LPS+ EGF group.PBS 0.1 ml was intraperitoneally injected in group C. EGF 10 μg (0.1 ml) was intraperitoneally injected in group EGF.The equal volume of PBS and EGF 10 μg was intraperitoneally injected at 12 h after tracheal infusion of LPS in group LPS+ PBS and group LPS+ EGF, respectively.EGF receptor (EGFR) antagonist AG1478 1 mg was intraperitoneally injected, 30 min later LPS was tracheally instilled, and 12 h later EGF 10 μg was intraperitoneally injected in group AG1478+ LPS+ EGF.ARDS model was developed by endotracheal instillation of LPS 3 mg/kg.The mice were sacrificed on the 1st and 5th days after development of the model, and lung tissues were obtained for microscopic examination of the pathological changes which were scored after HE staining.Bronchoalveolar lavage was performed on 5th day after development of the model and before sacrifice, and bronchoalveolar lavage fluid (BALF) was collected to detect total protein concentration (by BCA method) and IL-6 and TNF-α concentrations (by enzyme-linked immunosorbent assay). Lung tissues were obtained for determination of the wet/dry lung weight ratio (W/D ratio), expression of lung surfactant associated protein C (SP-C) and proliferating nuclear antigen (PCNA) (by immunofluorescence method), and expression of EGFR, phosphorylated EGFR (p-EGFR), protein kinase B (Akt), and phosphorylated Akt (p-Akt) (by Western blot). Results:Compared with group C, the pathological score, W/D ratio, concentrations of total protein, IL-6 and TNF-α in BALF and neutrophil count were significantly increased, the number of cells co-expressing SP-C and PCNA was increased, and p-EGFR/EGFR and p-Akt/Akt ratios were increased in group LPS+ PBS ( P<0.01), and no significant change was found in the indexes mentioned above in group EGF ( P>0.05). Compared with group LPS+ PBS, the pathological score, W/D ratio, concentrations of total protein, IL-6 and TNF-α in BALF and neutrophil count were significantly decreased, the number of cells co-expressing SP-C and PCNA was increased, and p-EGFR/EGFR and p-Akt/Akt ratios were increased in group LPS+ EGF ( P<0.01). Compared with group LPS+ EGF, the pathological score, W/D ratio, concentrations of total protein, IL-6 and TNF-α in BALF and neutrophil count were significantly increased, the number of cells co-expressing SP-C and PCNA was decreased, and p-EGFR/EGFR and p-Akt/Akt ratios were decreased in group AG1478+ LPS+ EGF ( P<0.01). Conclusions:EGF can promote the repair of lung tissues in mice with ARDS, and the mechanism may be related to activation of EGFR signaling pathway and promotion of proliferation of alveolar epithelial cell type Ⅱ.

Based on the five core indicators (the case mix index, the proportion of level-4 surgery, the proportion of technical service income in medical income, the proportion of personnel expenditure in business expenditure, and the proportion of fixed part in personnel salary), the authors discussed the guiding significance of " paying attention to the medical level, strengthening the functional orientation, reflecting the technical value, highlighting people-orientation, and ensuring sustainable development" in the high-quality development of public hospitals. In combination with the current situation of a pilot hospital of high-quality development with the corporate supports of National Health Commission and Province Government, the authors explained the common bottlenecks of public hospitals, such as inaccurate functional positioning, weak innovation ability, poor finance structure, poor salary system and insufficient attention to talents. In the last, the authors pointed out that high-quality development was the development of deepening reform, innovation driven, structural optimization, talent oriented, people-oriented and under the leadership of the Communist Party of China, and put forward targeted implementation paths to provide reference for the pilot work.

Objective To evaluate the effect of united Organ Procurement Organization (OPO) on organ donation and procurement quality control indexes. Methods The differences in organ donation workload, work efficiency, organ donation quality control and management indexes in a united OPO-led hospital were retrospectively analyzed before (n=36) and after (n=33) the establishment of united OPO. Results After the establishment of united OPO, the organ donation workload and efficiency were enhanced. The annual donation cases, annual organ procurement cases, average organ procurement cases per day, organ donation rate of per million population (PMP), coordinator work efficiency index and other indexes were further improved. Before the establishment of united OPO, the donation conversion rate was 26.5%, and increased up to 29.0% after the establishment of united OPO. The average organ yield rate remained higher than 3.3 before and after the establishment of united OPO. No significant differences were noted in the utilization rate of procured organs, proportion of marginal donor organs, positive rate for pathogen culture in organ preservation solution, the incidence of primary nonfunction (PNF) and delayed graft function (DGF) before and after the establishment of united OPO (all P > 0.05). The biopsy rates of donated organs were 27.7% and 58.3%, and the organ outflow rates were 83.1% and 47.8% before and after the establishment of united OPO, and the differences were statistically significant (both P < 0.05). Conclusions The establishment of united OPO contributes to promoting efficient development of organ donation and procurement, lowering the cost of organ donation and procurement, and improving the effectiveness, quality control and management levels of organ donation and procurement.