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.

Objective:To compare the efficacy of unilateral percutaneous kyphoplasty (PKP) and unilateral PKP combined with posterior medial branch block of the contralateral spinal nerve in the treatment of lumbar osteoporotic vertebral compression fracture (OVCF) in the elderly.Methods:A retrospective cohort study was conducted to analyze the clinical data of 161 aged patients with newly developed lumbar OVCF, admitted to Xi′an Central Hospital Affiliated to Xi′an Jiaotong University School of Medicine from January 2019 to January 2023, including 58 males and 103 females, aged 61-88 [(72.9±6.3)years]. All the patients were diagnosed with type II compression fracture based on acute symptomatic osteoporotic thoracolumbar fracture classification (ASOTLF). Seventy-eight patients underwent unilateral PKP (PKP group), while the other 83 patients underwent unilateral PKP combined with posterior medial branch block of the contralateral spinal nerve (PKP+contralateral block group). The operation time, intraoperative blood loss, and length of hospital stay were recorded. Beck index of the injured vertebra, Cobb angle of lumbar lordosis, Roland-Morris disability (RMD) score, visual analogue scale (VAS), and Oswestry disability index (ODI) were evaluated before operation, at 1 day, 1 week, 1 month, 3 months after operation, and at the last follow-up. The incidence of complications such as cement leakage was recorded as well.Results:All the patients were followed up for 6-8 months [(6.7±0.6)months]. There were no significant differences between the two groups in the operation time, intraoperative blood loss, or length of hospital stay ( P>0.05). The Beck index of the injured vertebra and Cobb angle of lumbar lordosis were not significantly different between the two groups before operation, at 1 day, 1 week, 1 month, 3 months after operation, and at the last follow-up ( P>0.05). The RMD score of the injured vertebra, VAS score, and ODI were not significantly different between the two groups before operation ( P>0.05). At 1 day, 1 week, 1 month, 3 months after operation, and at the last follow-up, the RMD scores in the PKP+contralateral block group were (11.23±1.05)points, (10.90±1.11)points, (10.10±1.06)points, (9.94±1.06)points, and (9.60±0.83)points respectively, which were all lower than (17.55±0.71)points, (15.78±0.86)points, (13.42±0.92)points, (10.67±0.78)points, and (9.78±0.72)points in the PKP group ( P<0.05 or 0.01); the VAS scores in the PKP+contralateral block group were (3.02±0.60)points, (2.96±0.55)points, (2.92±0.57)points, (2.88±0.61)points, and (2.70±0.51)points respectively, which were all lower than (3.60±0.57)points, (3.47±0.55)points, (3.32±0.46)points, (2.99±0.47)points, and (2.77±0.42)points in the PKP group ( P<0.05 or 0.01); the ODI values in the PKP+contralateral block group were 14.43±1.29, 14.54±1.24, 14.63±1.32, 14.37±1.31, and 13.42±1.45 respectively, which were all lower than 16.72±1.64, 16.09±1.49, 14.82±1.53, 14.74±1.46, and 13.69±1.75 in the PKP group ( P<0.05 or 0.01). The bone cement leakage rate was 12.0% (10/83) in the PKP+contralateral block group, similar to 11.5% (9/78) in the PKP group ( P>0.05). No other complications such as neurovascular injury, pulmonary embolism or adjacent vertebral fracture were found in either groups. Conclusion:In the treatment of lumbar OVCF in the elderly, unilateral PKP combined with posterior medial branch block of the contralateral spinal nerve is similar to unilateral PKP in terms of the operation time, intraoperative blood loss, length of hospital stay, effectiveness of reduction, and incidence of complications, but it can achieve better pain relief and more satisfactory functional recovery.

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.

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.

Background: Cardiopulmonary resuscitation (CPR) strategies in COVID-19 patients differ from those in patients suffering from cardiogenic cardiac arrest. During CPR, both healthcare and non-healthcare workers who provide resuscitation are at risk of infection. The Working Group for Expert Consensus on Prevention and Cardiopulmonary Resuscitation for Cardiac Arrest in COVID-19 has developed this Chinese Expert Consensus to guide clinical practice of CPR in COVID-19 patients. Main recommendations: 1) A medical team should be assigned to evaluate severe and critical COVID-19 for early monitoring of cardiac-arrest warning signs. 2) Psychological counseling and treatment are highly recommended, since sympathetic and vagal abnormalities induced by psychological stress from the COVID-19 pandemic can induce cardiac arrest. 3) Healthcare workers should wear personal protective equipment (PPE). 4) Mouth-to-mouth ventilation should be avoided on patients suspected of having or diagnosed with COVID-19. 5) Hands-only chest compression and mechanical chest compression are recommended. 6) Tracheal-intubation procedures should be optimized and tracheal-intubation strategies should be implemented early. 7) CPR should be provided for 20-30 min. 8) Various factors should be taken into consideration such as the interests of patients and family members, ethics, transmission risks, and laws and regulations governing infectious disease control. Changes in management: The following changes or modifications to CPR strategy in COVID-19 patients are proposed: 1) Healthcare workers should wear PPE. 2) Hands-only chest compression and mechanical chest compression can be implemented to reduce or avoid the spread of viruses by aerosols. 3) Both the benefits to patients and the risk of infection should be considered. 4) Hhealthcare workers should be fully aware of and trained in CPR strategies and procedures specifically for patients with COVID-19.

Objective: To investigate the prevalence of chronic diseases in aged ≥80 oldest-olds and related factors influencing their daily activities. Methods: This survey was conducted in the retired cadres in Beijing from 2012 to 2014. A unified questionnaire was used to investigate the general characteristics of the oldest-olds and the activities of daily living (ADL). Information on chronic diseases was extracted from related medical records. Results: A total of 4 472 male oldest- olds, with an average age as (87.1±3.9) years (80-102 years), were included. Nearly half of the elderly people were suffering from 5 or more kinds of chronic diseases, with 43.9% of them having disability on basic daily activities (BADL) with 13.4% of those classified as moderate or severe cases. 38.8% of them had instrumental activities of daily living (IADL) disability, with 28.7% of them were moderate or severe cases. The ADL disability showed an increasing trend along with the increase number of chronic diseases. The proportion of BADL disability increased from 40.5% to 50.6%. Compared with the ones having fewer chronic diseases (≤2 kinds), those with more (≥7 kinds) had an increase of 50.5% risk on BADL disability and 199.4% on IADL disability. Conclusion We noticed that the male oldest-olds suffered from multiple chronic diseases. The impairment of ADL was higher than the younger elderly. Comorbidity showed heavier impact on ADL, especially on the instrumental activities of daily living.

Objective To indentify the cognitive status of Chinese patients to acne and the influencing factors to theirs' cognitive status,so as to provide solid evidences for the prevention and treatment of acne.Methods A self-designed questionnaire was made to conduct this survey of 16,156 acne patients,who seeked to the treatment in the dermatological departments from 112 hospitals in China.The survey consisted of several parts,including the general status of patients,the patients' cognition of occurrence,development and risk factors of acne,whether the first choice was seeking treatment at the hospital when the patients had acne and the condition of selection of skin care products.The factors were analyzed,which could impact the cognition of the patients' behavior of treatment,how did the patients' cognition to influence their medical behavior and skin care as well as the consistency of assessment of the severity of acne by doctors and patients themselves.Results The acne patients studied had the best knowledge of "acne is a skin disease","it not only occurs in the period of adolescence" and "the disease can be prevented and cured",which accordingly accounted for 80.65％,69.16％ and 65.49％ of the total patients respectively.However,the awareness of acne patients to heredity,high sugar and dairy products as risk factors for acne was insufficient,which accounted for 48.72％,42.40％ and 18.25％ of the total patients,respectively.Gender,age,educational level,occupation and health knowledge were the main factors affecting the cognitive level of patients;the survey also found that men,patient with educational level of junior high or even lower educational condition,occupation of labor workers or farmers and patients were lack of health education with poor knowledge of the genetics and dietary were risk factors for acne;patients with age over 36 years or with mild illness had poor knowledge of dietary risk factors for acne;the difference was statistically significant (P＜0.05).The analysis of the influence of cognitive status on medical treatment behavior and skin care showed that the better the cognition,the higher the probability of patients would choose medical treatment as the first choice as well as choosing functional skin care products;the difference was statistically significant (P＜0.05).The consistency of assessment of the severity of acne by doctors and patients was poor (Kappa value ＜0.4),and the assessment of severity of acne by patients was more serious than doctors' assessment.Conclusions Patient's cognitive status will affect their medical behavior and skin care,and there is also a phenomenon that patients have a more serious assessment of their acne condition.It is suggested that health education for acne patients should be strengthened in clinical medicine so as to improve their knowledge of acne as well as preventing from acne effectively.

The accelerating growth of the public microbial genomic data imposes substantial bur-den on the research community that uses such resources. Building databases for non-redundant ref-erence sequences from massive microbial genomic data based on clustering analysis is essential. However, existing clustering algorithms perform poorly on long genomic sequences. In this article, we present Gclust, a parallel program for clustering complete or draft genomic sequences, where clustering is accelerated with a novel parallelization strategy and a fast sequence comparison algo-rithm using sparse suffix arrays (SSAs). Moreover, genome identity measures between two sequences are calculated based on their maximal exact matches (MEMs). In this paper, we demon-strate the high speed and clustering quality of Gclust by examining four genome sequence datasets. Gclust is freely available for non-commercial use at https://github.com/niu-lab/gclust. We also introduce a web server for clustering user-uploaded genomes at http://niulab.scgrid.cn/gclust.

Objective To explore the composition principles of prescriptions for simple obesity based on the analysis of medical literature issued in recently 30 years about Chinese medicine for simple obesity. Methods We collected literature of Chinese medicine in treating simple obesity from VIP, CNKI, Wanfang, CBM and CMCC/CMCI databases, and screened out the formulas for simple obesity to establish a formula database. And then the medication rules were figured out with the Traditional Chinese medicine Inheritance Support System version 2.5 (TCMISS 2.5) software. Results A total of 57 formulas were screened out. And the top 10 herbs with highest occurrence frequency in the prescriptions were Poria, Rhizoma Atractylodis Macrocephalae, Rhizoma Alismatis, Radix et Rhizoma Rhei, Fructus Crataegi, Radix Astragali, Radix Glycyrrhizae, Folium Nelumbinis, Pericarpium Citri Reticulatae and Semen Cassiae. After data mining, we got 13 high-frequency herb-pair combinations and 31 core combinations, and 8 new prescriptions were extracted. Conclusion The research has achieved the quantitative description of the relationship between the Chinese medicines, the extraction of the core combinations and the discovery of new Chinese medicine prescriptions for simple obesity. The results will provide references for the development of new Chinese medicines for the treatment of simple obesity .

8 cases of children with bilateral mixed cleft lip were repaired by two staged surgeries .Results showed that the incision of the two staged surgeries was healed in phase Ⅰ.After the second -staged surgery, the height of bilateral lips was almost symmetrical, the bilateral nostrils had good symmetry and the red lip had natural form .The research shows that the operational effect of the repair for bilateral mixed cleft lip is good by two staged surgeries . The method can be accepted by the children 's family, it is worth promoting.