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 and objective The pathological types of lung ground glass nodules(GGNs)show great significance to the clinical treatment.This study was aimed to predict pathological types of GGNs based on computed tomog-raphy(CT)quantitative parameters.Methods 389 GGNs confirmed by postoperative pathology were selected,including 138 cases of precursor glandular lesions[atypical adenomatous hyperplasia(AAH)and adenocarcinoma in situ(AIS)],109 cases of microinvasive adenocarcinoma(MIA)and 142 cases of invasive adenocarcinoma(IAC).The morphological characteristics of nodules were evaluated subjectively by radiologist,as well as artificial intelligence(AI).Results In the subjective CT signs,the maximum diameter of nodule and the frequency of spiculation,lobulation and pleural traction increased from AAH+AIS,MIA to IAC.In the AI quantitative parameters,parameters related to size and CT value,proportion of solid component,energy and entropy increased from AAH+AIS,MIA to IAC.There was no significant difference between AI quantitative parameters and the subjective CT signs for distinguishing the pathological types of GGNs.Conclusion AI quantitative parameters were valu-able in distinguishing the pathological types of GGNs.

Objective To evaluate the predictive value of CT-enhanced imaging-based radiomics nomogram for the status of microsatel-lite instability(MSI)in colon cancer.Methods A retrospective analysis was conducted on 129 postoperative colon cancer patients with confirmed MSI status.They were randomly divided into a training group(n=90)and a validation group(n=39)at a ratio of 7:3.Radiomics features were extracted from preoperative CT-enhanced images of the patients.The predictive performance of various machine learning algorithms was evaluated using the area under the curve(AUC).A nomogram model was developed by incorporating clinical independent risk factors,and the model's overall performance was assessed using decision curve analysis(DCA).Results Age and lesion site were identified as prominent independent risk factors and utilized in the construction of a clinical model.The light gradient boosting machine(LightGBM)algorithm was chosen for building a radiomics model.As a joint model,the AUC of the nomogram model of 0.917 in the training group and 0.822 in the validation group.The DCA confirmed the substantial clinical applicability of the nomogram model.Conclusion The CT-enhanced imaging-based radiomics nomogram offers a pioneering and individualized predic-tive approach for determining the MSI status in colon cancer.

Objective    To compare the clinical efficacy between right visual double lumen tube (VDLT) intubation and right common double lumen tube (DLT) intubation in lung isolation technique. Methods    A total of 57 patients undergoing thoracoscopic surgery with right DLT lung isolation technique in the First People's Hospital of Chenzhou City and West China Hospital from June 2020 to June 2021 were randomly divided into two groups: a DLT group (n=29, 16 males and 13 females, with a mean age of 54.3±13.2 years) and a VDLT group (n=28, 18 males and 10 females, with a mean age of 55.1±13.7 years) at 1 : 1 with random number table generated by the computer. The clinical data of the two groups were compared. Results    Compared with the DLT group, the catheter positioning time in the VDLT group was statistically shorter (74.9±47.5 s vs. 151.6±88.9 s, P<0.001), the right upper lung occlusion rate (21.4% vs. 51.7%) and the intraoperative re-adjustment catheterization rate (14.3% vs. 48.3%) were lower (P<0.05). The quality of lung collapses immediately after thoracotomy (67.9% vs. 24.1%) and 20 minutes after thoracotomy (100.0% vs. 75.9%) were improved (P<0.05). There was no significant difference in the rate of fiberoptic bronchoscope assistance for positioning, or the incidence of pharynx pain and hoarseness between the two groups (P>0.05). Conclusion    Compared  with common DLT, VDLT is more efficient, accurate and intuitive in the location of right bronchial intubation.

Certification ; Laboratories

Objective To investigate the feasibility of the CT texture analysis (CTTA)in differentiating autoimmune pancreatitis (AIP)from pancreatic ductal adenocarcinoma (PDAC).Methods 25 patients with AIP and 31 patients with PDAC who confirmed by pathological or clinical underwent pretreatment three-phase contrast-enhanced CT were enrolled.Histogram parameters (mean CT values,median CT values,25 th,75 th percentile CT values,skewness,kurtosis,entropy and uniformity)were derived from CT images through texture analysis.The differences of histogram parameters between AIP and PDAC groups were compared.ROC and AUC were used to evaluate the diagnostic efficacy of histogram parameters in differentiating AIP from PDAC.Results The values for mean CT values,median CT values,25 th,75 th percentile CT values and uniformity of AIP were significantly higher than those of PDAC group,while the values for entropy of AIP were significantly lower than those of PDAC group in arterial phase,portal phase,and delay phases (all P＜0.05). There were no significant differences in kurtosis and skewness between AIP and PDAC groups (all P＞0.05).The uniformity in portal phase achieved the optimal diagnostic accuracy in differentiating AIP from PDAC (AUC＝0.973 ),the cutoff value was 0.797,the corresponding sensitivity and specificity were 92% and 9 6.8%,respectively.Conclusion CTTA can be used as a quantitative analysis method for differential diagnosis between AIP and PDAC,providing a reference for clinicians to select therapeutic schedules.

Objective To evaluate the clinical outcomes of split fractures of humeral greater tuberosity treated by our self-designed new type of anatomical locking plate.Methods From September 2012 to February 2017,23 patients were treated for acute split fracture of the humeral greater tuberosity using our self-designed new type of anatomical locking plate.They were 13 males and 10 females with a mean age of 52.8 years (range,from 25 to 81 years).Of them,6 were beyond 60 years old, 12 had comminuted fracture,10 were complicated with glenohumeral dislocation,and 12 with rotator cuff tear.The patients were evaluated clinically with Constant-Murley score,visual analog scale (VAS),range of motion and complications at the last follow-ups.Results This series were followed up for 12 to 30 months (mean,23.2 months).All the fractures healed after an average time of 10.6 weeks (range,from 8 to 12 weeks).Their mean Constant-Murley Score was 92.1 points (range,from 70 to 100 points),giving an excellent and good rate of 95.7％ (22/23);their VAS scores averaged 0.8 points (range,from 0 to 4 points).Their forward flexion averaged 160.6°,abduction 157.8°,external rotation 46.4°,and internal rotation up to the T11 level,respectively.Their complications rate was 17.4％ (4/23).One case of axillary nerve injury,one case of relapse of glenohumeral dislocation at sports,and 2 cases of stiff shoulder were observed.Conclusion Split fractures of the humeral greater tuberosity can be successfully treated with our new type of anatomical locking plate which serves as a new alternative treatment.

Objective The purpose of this study was to investigate the value of serum galactomannan (GM) in the diagnosis of invasive pulmonary aspergillosis (IPA) in patients with chronic obstructive pulmonary disease (COPD).Methods We enrolled 60 COPD patients in the study, including 19 IPA and 41 non-IPA cases.We examined serum GM of the patients by ELISA, evaluate the value of serum GM test for the diagnosis of IPA in patients with COPD, and compared the GM values before and after treatment.Results With 0.5 as the positive cutoff value, the sensitivity, specificity, positive predictive value, and negative predictive value of serum GM were 57.9%, 95.3%, 84.6%, and 83.0%, respectively, with a high specificity and a low sensitivity.The 7 IPA cases showed a significantly decreased GM value after treatment as compared with the baseline (0.30±0.21 vs 1.48±1.37, P=0.004).Conclusion The serum GM test has a limited value in the diagnosis of IPA in patients with COPD, but dynamic monitoring of the changes of the serum GM value may help evaluate the patient's condition.

Based on the analysis of blended learning characteristics, a blended learning pro-cess model including preliminary analysis, learning activities design, blended evaluation was con-structed. Then, a blended learning case study was carried out by taking the Fourth Military Medical University Information Security course as an example. The implement methods of setting learning goal, selecting learning content, constructing learning environment, organizing learning activities and course evaluation, were described in detail. Lastly, from the effectiveness questionnaire, it could be shown that blended learning motivated the learners' enthusiasm significantly. In order to improve the learning performance, we proposed that blended learning activities must be flexible and adaptive,and integrate face-to-face learning with online learning effectively.

Objective To realize the contamination status of dental unit waterlines (DUWL)in general hospitals, and provide scientific evidence for making preventive measures.Methods Three hospitals were selected for study, water source adopted by hospital A,B and C was running water,reservoir water,and filtered water through reverse osmosis filtration system respectively,specimens of dental handpiece spray water and flushing water of dental chair units were collected quarterly,total bacterial colony in water were detected.Results The qualified rate of source wa-ter,handpiece spray water,and flushing water in hospital A was 75.00%(3/4),0 (0/40)and 0 (0/40)respectively,col-ony count of handpiece spray water and flushing water was (1.20×103 -5.53×104 )CFU/mL(M=3.80×104 CFU/mL) and (2.11×104 -1.66×105 )CFU/mL(M=4.80×104 CFU/mL)respectively.The qualified rate of source water,hand-piece spray water,and flushing water in hospital B was 50.00%(2/4),60.00%(24/40)and 72.50%(29/40)respectively, colony count of handpiece spray water and flushing water was (0.00 -3.71 ×106 )CFU/mL(M=83.00 CFU/mL)and (0.00-2.39×106 )CFU/mL(M=72.00 CFU/mL)respectively.The qualified rate of source water,handpiece spray wa-ter,and flushing water in hospital C was 100.00%(4/4),55.00%(22/40)and 65.00%(26/40)respectively,colony count of handpiece spray water and flushing water was (0.00-6.20×103 )CFU/mL(M=96.00 CFU/mL)and(0.00-1.63×103 )CFU/mL(M=87.50 CFU/mL)respectively.Conclusion Water of DUWL in general hospitals is seriously con-taminated,disinfection and standardized management of source water and DUWL must be strengthened.