Objective: To analyze the process of handling a pulmonary tuberculosis(TB) outbreak among senior high school students in a boarding school in Chongqing, as well as to investigate the underlying causes of the outbreak, so as to provide evidence to inform TB prevention and control strategies in school settings. Methods: From November 2023 to April 2024, an epidemiological investigation was conducted into the TB outbreak in a grade 12 class from a boarding high school. Suspected cases were screened using symptom screening, tuberculin skin test (TST), and chest X-ray examinations. Confirmed cases underwent individual epidemiological interviews and sputum culture; Cultured positive mycobacterial strains were subjected to whole genome sequencing after identification as Mycobacterium tuberculosis. Results: A total of 10 active pulmonary TB cases were identified, all from the same class, yielding a student attack rate of 16.67%. Three isolates were culture positive, as well as all strains were of L2 type，and the WGS analysis of the strains suggested a common transmission chain. Excluding the index case, four additional cases were detected through symptom driven health care visits. Notably, 70% of patients presented with "chest tightness and chest pain" symptoms, and 50% had "cough" symptoms,but none were detected during morning health checks or tracking of absences due to illness. A total of 326 contacts were identified and underwent three rounds of screening and one follow up examination. In the initial screening, 35 close contacts from the same class showed strong TST positivity, corresponding to a strong positivity rate of 55.56%, significantly higher than the 20.76% observed among casual contacts ( χ 2=29.80, P <0.01). Among the 35 strongly TST positivvity close contacts and five individuals with moderate TST positivity whose induration had increased by ≥10 mm over two years, none received timely preventive treatment initially; five of them were subsequently diagnosed with active TB within three months. Following this, 25 individuals initiated preventive therapy, resulting in a preventive treatment initiation rate of 62.50%. Among TST negative classmates who converted to strong positivity on repeat TST testing at three months, 75.00% started preventive treatment, but only 22.22% completed the full course. Conclusion Inadequate implementation of morning health checks and cause tracking for absenteeism due to illness, poorly standardized screening procedures, and delayed preventive treatment may have been key factors contributing to the spread of the outbreak.

ObjectiveTo investigate the association between metabolic associated fatty liver disease （MAFLD） and the risk of atherosclerotic cardiovascular disease （ASCVD）， and to provide data support for the prevention and treatment of such metabolic-associated diseases in clinical practice. MethodsAn observation cohort was established for the workers of Kailuan who underwent physical examination for the first time from June 2006 to October 2007 and had complete liver assessment data， without the history of malignant tumor， MAFLD or ASCVD. According to the presence or absence of MAFLD， the patients were divided into non-MAFLD group with 67 565 patients and MAFLD group with 29 004 patients， and according to the presence or absence of ASCVD， the patients were divided into non-ASCVD group with 69 141 patients and ASCVD group with 481 patients. The group t-test or the Wilcoxon rank-sum test was used for comparison of continuous data between the two groups. The χ² test was used for comparison of categorical data between the two groups. The life-table method was used to calculate the cumulative incidence rates of new-onset ASCVD and MAFLD； the Kaplan-Meier method was used to plot the survival curves of the cumulative incidence rates of ASCVD in the MAFLD group and the non-MAFLD group and the cumulative incidence rates of MAFLD in the ASCVD group and the non-ASCVD group， and the log-rank test was used for comparison of cumulative incidence rates between two groups. A multivariate Cox proportional-hazards regression model analysis was used to investigate the impact of MAFLD on the risk of ASCVD and the impact of ASCVD on the risk of MAFLD. ResultsCompared with the non-MAFLD group， the MAFLD group had significantly higher levels of body mass index （BMI）， waist circumference， systolic blood pressure （SBP）， diastolic blood pressure （DBP）， resting heart rate， alanine aminotransferase， uric acid （UA）， fasting blood glucose （FBG）， triglyceride （TG）， total cholesterol， low-density lipoprotein cholesterol， and high sensitivity C-reactive protein （hs-CRP）， as well as significanty lower levels of estimated glomerular filtration rate （eGFR） and high-density lipoprotein cholesterol （all P <0.05）. Compared with the non-ASCVD group， the ASCVD group had significantly higher levels of BMI， waist circumference， SBP， DBP， UA， FBG， TG， and hs-CRP and a significantly lower level of eGFR （all P<0.05）. The incidence rate of new-onset ASCVD continued to increase over time in the MAFLD group and the non-MAFLD group， while the incidence rate of new-onset MAFLD firstly increased and then remained stable over time in the ASCVD group and the non-ASCVD group. There were 4 263 cases （14.70%） of new-osnet ASCVD in the MAFLD group， with an incidence density of 12.90 per 1 000 person-years， while there were 6 529 cases （9.66%） of new-osnet ASCVD in the non-MAFLD group， with an incidence density of 8.24 per 1 000 person-years， and there were significant differences in the incidence density and cumulative incidence rate of ASCVD between the two groups （χ²=519.09 and 531.80， both P<0.05）. There were 148 cases （30.77%） of new-onset MAFLD in the ASCVD group， with an incidence density of 40.10 per 1 000 person-years， while there were 32 194 cases （46.56%） of new-onset MAFLD in the non-ASCVD group， with an incidence density of 57.59 per 1 000 person-years， and there were significant differences in the incidence density and cumulative incidence rate of MAFLD between the two groups （χ²=19.29 and 30.78， both P<0.05）. The corrected multivariate Cox proportional-hazards regression model analysis showed that MAFLD was a risk factor for new-onset ASCVD （hazard ratio ［HR］=1.11， 95% confidence interval ［CI］： 1.06 — 1.16， P<0.001）， while ASCVD was a protective factor against new-onset MAFLD （HR=0.72， 95%CI： 0.61 — 0.85， P<0.001）. ConclusionThere is a significant association between MAFLD and ASCVD， with an increase in the risk of ASCVD in the MAFLD population and a reduction in the risk of MAFLD in the ASCVD population.

Objective To explore the longitudinal associations of body roundness index (BRI), visceral adiposity index (VAI), and metabolic score for visceral fat (METS-VF) with the risk of new-onset atrial fibrillation (AF). Methods This study included participants from the UK Biobank who were free of AF or pregnancy at baseline and completed the first and second assessments of BRI, VAI, and METS-VF. The changes in BRI, VAI, and METS-VF were classified using K-means clustering analyses, and the cumulative adiposity indices were also calculated. The primary outcome was new-onset AF. Three Cox regression models were employed to investigate the longitudinal associations of the BRI, VAI, and METS-VF changes with the risk of incident new-onset AF. The results were presented as hazard ratios (HRs) and the corresponding 95% confidence intervals (CIs). Restricted cubic spline analyses were performed to explore potential non-linear associations between baseline or cumulative adiposity indices and the risk of new-onset AF. C-index analyses were conducted to evaluate the predictive value of BRI, VAI, and METS-VF for new-onset AF. Subgroup analyses were performed according to age, gender, race, smoking status, alcohol consumption, and physical activity. Polygenic risk scores were applied to account for genetic susceptibility and investigate potential interactions between adiposity indices and genetic risk. Univariate linear regression analyses were performed to evaluate the relationships of cumulative adiposity indices and magnetic resonance imaging and dual X-ray absorptiometry parameters, including visceral adipose tissue (VAT) volume, VAT mass, trunk fat volume, and trunk fat mass. We further applied the eXtreme Gradient Boosting (XGBoost) algorithm, with the feature importance being measured to evaluate the predictive value of each adiposity index for imaging parameters. Mendelian randomization analysis was further conducted to investigate the potential causal relationship between trunk fat mass and AF. Results A total of 12 776 participants were included. Over a median follow-up of 9.60 years, 761 (5.96%) new-onset AF events were recorded. Participants were divided into four classes based on the changes in adiposity indices. In the fully adjusted model, compared to participants in Class 1 of BRI, those in Class 3 (HR＝1.30, 95%CI 1.04-1.63, P＝0.023) and Class 4 (HR＝2.17, 95%CI 1.61-2.93, P＜0.001) were associated with significantly higher risks of new-onset AF. Regarding METS-VF, participants in Class 4 of METS-VF also demonstrated a significantly higher risk of new-onset AF compared to those in Class 1 (HR＝1.66, 95%CI 1.15-2.39, P＝0.007). However, no significant association was observed between different classes of VAI and the risk of new-onset AF. For every 1 standard deviation increase in cumulative BRI, VAI, and METS-VF, the fully adjusted HRs of new-onset AF were 1.23 (95%CI 1.13-1.35), 1.02 (95%CI 0.94-1.10), and 1.23 (95%CI 1.12-1.35), respectively. Cumulative adiposity indices (BRI, VAI, and METS-VF) were divided into quartiles. Using the first quartile as reference, participants in the highest quartiles of BRI (HR＝1.40, 95%CI 1.10-1.79, P＝0.007) and METS-VF (HR＝1.44, 95%CI 1.13-1.83, P＝0.003) both exerted a significantly higher risk of new-onset AF. Regarding VAI, no significant association was observed (HR＝1.00, 95%CI 0.81-1.23, P＝0.988). Restricted cubic spline analyses revealed non-linear relationships between cumulative BRI, baseline/cumulative VAI, and baseline/cumulative METS-VF with new-onset AF risk (all P_overall＜0.05, P_non-linear＜0.05). In the C-index analysis, BRI demonstrated the highest predictive performance for new-onset AF, followed by METS-VF and VAI. Subgroup analysis indicated a stronger association between METS-VF and the risk of new-onset AF amongst participants younger than 60 years (P_interaction＝0.008). Polygenic risk score analysis stratified by genetic risk demonstrated a synergistic effect between BRI and genetic risk with new-onset AF, with the overall risk of new-onset AF increasing as both BRI and genetic risk increased. Linear regression analysis revealed a positive correlation between cumulative BRI with VAT volume, VAT mass, trunk fat volume, and trunk fat mass. The feature importance plot derived from the XGBoost algorithm indicated that cumulative BRI had the greatest predictive value on VAT volume, VAT mass, trunk fat volume, and trunk fat mass. Mendelian randomization analysis confirmed a significant causal relationship between trunk fat mass and AF. Conclusions There are significant non-linear associations between BRI, METS-VF, and VAI with new-onset AF. Higher BRI and METS-VF are significantly associated with a higher risk of new-onset AF, whereas no significant association is observed for the VAI. BRI exhibits a positive correlation with VAT and trunk fat, and demonstrates superior performance in predicting new-onset AF compared to VAI and METS-VF. Monitoring and managing BRI may be important in the early detection and intervention of AF.

ObjectiveTo investigate the association between cumulative atherogenic index of plasma （cumAIP） and the risk of new-onset nonalcoholic fatty liver disease （NAFLD） in young and middle-aged individuals. MethodsA prospective cohort study was conducted among the young and middle-aged individuals （aged 18 to <60 years） in the Kailuan study cohort who underwent physical examination in Kailuan General Hospital and its 10 affiliated hospitals in June 2006 to October 2010， and after screening based on the inclusion and exclusion criteria， 33 987 individuals were included in the observation cohort. The individuals were divided into Q1， Q2， Q3， and Q4 groups based on the quantiles of cumAIP. The Kaplan-Meier method was used to calculate the cumulative incidence rate of new-onset NAFLD in the four groups， while the log-rank test was used for comparison between groups. A multivariate Cox regression analysis was used to obtain the hazard ratio （HR） and 95% confidence interval （CI） of the risk of new-onset NAFLD in the four groups. A one-way analysis of variance was used for comparison of normally distributed continuous data between multiple groups， and the Kruskal-Wallis H test was used for comparison of non-normally distributed continuous data between multiple groups； the chi-square test was used for comparison of categorical variables between groups. ResultsThe mean follow-up was 10.89±2.54 years， and there were 6 011 cases of new-onset NAFLD， including 995 cases in the Q1 group， 1 366 in the Q2 group， 1661 in the Q3 group， and 1 989 in the Q4 group， with an incidence density of 11.37， 16.02， 19.97， and 24.91 per thousand person-years. The log-rank test showed that there was a significant difference in cumulative incidence rate between the four groups （P<0.001）. With the presence or absence of NAFLD as the dependent variable and the quantiles of different exposure levels to cumAIP as the independent variable， the multivariate Cox regression model analysis showed that compared with the Q1 group， the Q2， Q3， and Q4 groups had an HR of 1.30 （95%CI： 1.20 — 1.41）， 1.52 （95%CI： 1.41 — 1.65）， and 1.79 （95%CI： 1.64 — 1.95）， respectively， for new-onset NAFLD， with a P_trend value of <0.001. With the presence or absence of new-onset NAFLD as the dependent variable and the cumulative exposure to AIP for 0， 2， 4， and 6 years as the independent variable， the Cox regression analysis showed that compared with cumulative exposure to AIP for 0 years， cumulative exposure to AIP for 2， 4， and 6 years had an HR of 1.24 （95%CI： 1.15 — 1.35）， 1.51 （95%CI： 1.40 — 1.64）， and 1.70 （95%CI： 1.56 — 1.84）， respectively， with a P_trend value of <0.001. A sensitivity analysis was performed after exclusion of the individuals with new-onset NAFLD within 2 years， the individuals who experienced atherosclerotic cardiovascular disease events during follow-up， and the individuals taking antihypertensive， hypoglycemic， and lipid-lowering drugs， and the results were similar to those of the main analysis. Considering the competitive relationship between all-cause death and outcome events， a competing risk analysis of death was performed， which showed that the results of risk analysis were similar to those of the main analysis. ConclusionA high level of cumAIP exposure can increase the risk of new-onset NAFLD in young and middle-aged individuals.

Objective To explore the prevalence of 9 respiratory pathogens from March 2023 to February 2024,as well as the detection efficiency of various methods for pathogens.Methods A retrospective analysis was conducted on the detection of 9 pathogens in 38 948 patients who first presented with respiratory symp-toms from March 2023 to February 2024,as well as the detection efficacy of nucleic acid,antigen,antibody and other methods.Results Firstly,among 38 948 patients,a total of 8 345 cases(21.43%)were detected with at least one pathogen,of which 8 158 cases(20.95%)were detected with only one pathogen,and 187 cases(2.29%,187/8 158)were detected with two or more pathogens.The top three detection rates were SARS-CoV-2(20.37%),mycoplasma pneumoniae(MP,15.58%)and influenza A virus(IVA,10.79%).Secondly,among patients who detected at least one of the nine pathogens,the detection rate was 24.94%in autumn,21.45%in spring,18.54%in summer,and 19.22%in winter,and the difference in detection rates between the four seasons was statistically significant(P<0.001).Thirdly,except for the relatively high detection rates of SARS-CoV-2 in spring(51.24%)and summer(37.31%),and the highest detection rate of IVB in winter(11.28%),the detection rates of other pathogens were highest in autumn.Fourthly,there was a statistically significant difference in the total detection rates among the children group(31.83%),the youth group(12.48%),the middle-aged group(10.70%),and the elderly group(12.43%)(P<0.001).The detection rates of 7 pathogens,including MP,IVA,Influenza B virus(IVB),syncytial virus,CP,adenovirus,and parain-fluenza virus type 1,were highest in children,and there was a statistically significant difference in comparison between different age groups(P<0.05).The detection rate of SARS-CoV-2 in the children group(3.45%)was lower than that in other age groups(30.90%,29.09%,32.16%,P<0.001).There was no statistically significant difference in HPIV-3 between different age groups(P=0.478).Fifthly,there was no significant difference in overall detection rate between male and female(P>0.05).However,the detection rates of MP and CP in female were higher than those in male(P<0.05),while IVA in male was slightly higher than that in female(P=0.014).There were no significant differences in the detection rate of other 6 pathogens between female and male(P>0.05).Sixthly,the detection rate of MP antigen was lower than that of MP nucleic acid detection(P<0.001),and the detection rate of MP antibody detection was lower than that of MP nucleic acid detection(P<0.001).The detection rate of MP antibody detection increased significantly with the extension of time from initial symptoms to medical treatment(P<0.001).Seventhly,the detection rates of antigen of IVA,IVB,RSV and ADV were significantly lower than those of the corresponding nucleic acid(P<0.001),and the detection rates of nucleic acid testing for 4 kinds of pathogen was about 5 times that of the correspond-ing antigen testing(4.75-6.25 times).And the consistency of the detection rate between antigen detection and nucleic acid detection was poor(Kappa=0.046-0.239).Conclusion The prevalence of common respir-atory pathogens from March 2023 to February 2024 exhibits certain characteristics.Moreover,the detection ef-ficiency of different methods for pathogens varies greatly,and appropriate detection methods should be select-ed based on a thorough understanding of their performance.

Objective To investigate the effect of orthosis design parameters on correction of scoliosis and orthosis-trunk interface pressure.Methods A finite element model of scoliosis was constructed to simulate the assembly effect of the orthosis.The orthosis was divided into four loading areas(left rib,right rib,anterior-left and posterior-right area)to simulate six modification conditions.In Models 1,2 and 3,a fixed modification of 20 mm was applied on the anterior left and posterior right areas,while the displacement loads of 20,25 and 30 mm were applied on both the left rib and right rib areas.In Models 4,5 and 6,a fixed modification of 25 mm was applied on left rib and right rib areas,with the displacement loads of 15,20 and 25 mm applied on both anterior left and posterior right areas.The Cobb angle,apical vertebral rotation(AVR)and interface pressure were calculated.Results The correction of Cobb angle in Models 1,2 and 3 was 8.94°,15.62° and 17.91°,respectively,with AVR correction of 7.53°,6.69° and 5.87°,respectively.In Models 4,5 and 6,the correction of Cobb angle was 14.55°,15.62° and 16.09°,with AVR correction of 5.25°,6.69° and 8.63°,respectively.In Model 6,the correction rate of Cobb angle and AVR was 45.48%and 41.22%,respectively,with a maximum pressure of 26.51 kPa on orthosis-trunk interface,achieving the most significant outcome.Conclusions The modification of orthosis has a significant effect on the correction of Cobb and AVR angles.The loading on the left rib and right rib areas mainly affect the Cobb angle,while the loading on the anterior left and posterior right areas mainly affect the spinal axial-rotation.A modification of 25 mm on all loading areas achieves the optimal spinal correction.This study provides the quantitative data for orthosis design.

Objective:To investigate whether there is mitochondrial transfer in dental mesenchymal stem cells (MSCs) and its significance for the odontogenic differentiation.Methods:Flow cytometry and immunohistochemical staining were used to isolate dental mesenchymal stem cells. Immunofluorescence staining and live cell imaging were applied to determine whether there is mitochondrial transfer in dental MSCs. Transcriptome sequencing data re-analysis of human dental pulp stem cells (DPSCs) and bone marrow mesenchymal stem cells (BMSCs) from gene expression omnibus (GEO) data base demonstrated the importance of mitochondrial transfer in dental MSCs. Cells were managed with mitochondrial transfer inhibitor ML141 with dimethyl sulfoxide as the control. Immunofluorescence staining, senescence-associated β-galactosidase (SA-β-gal) staining, reactive oxygen species (ROS) assay, 5-ethynyl-2'-deoxyuridine(EdU) labelling, cell counting kit-8 (CCK-8) assay, Western blotting, live cell imaging and transmission electron microscope were used to investigate cell morphology, ROS level, cellular senescence, cell proliferation, MSCs marker paired related homeobox 1 (Prrx1) and Sp7 transcription factor (Sp7) expression, mitochondrial transfer and mitochondrial morphology, respectively. Further, after using ML141 during the induction of odontogenic differentiation, alkaline phosphatase (ALP) chromogenic kit was used to detect ALP activity and real-time fluorescence quantitative PCR (RT-qPCR) was used to detect the expression of odontogenic differentiation-related genes Alp, Sp7, dentin matrix protein 1 (Dmp1), and dentin salivary phosphoprotein (Dspp), which were applied to investigate the effect of mitochondrial transfer on odontogenic differentiation.Results:An ultrafine tunneling nanotubes (TNTs) structure labelled with F-actin existed between dental MSCs, and the presence of transferring mitochondria in this structure was also confirmed. Transcriptome sequencing data suggested that the gene expression profiles were significantly different between DPSCs and BMSCs. Genes related to mitochondrial transfer and mitochondrial dynamic were significantly increased in DPSCs compared to BMSCs. Compared with the control group, treatment with 1, 5, 10 μmol/L ML141, the mitochondrial transfer inhibitor, had little significant effects on the cell morphology, cytoskeleton and ROS level. SA-β-gal activity and the proportion of SA-β-gal positive cells in the ML141-treated groups [(3.93±0.21)%, (3.23±0.42)%, (4.06±0.84)%] had no significant differences with the control group [(3.83±0.28)%] (all P>0.05). In the cell proliferation assay, the proportion of EdU positive cells in the ML141-treated groups [(20.00±3.82)%, (19.48±1.96)%, (12.55±2.86)%] had no significant differences (all P>0.05) with the control group [(18.57±0.87)%], whereas the CCK-8 assay showed similar results in ML141-treated group of 1, 5 μmol/L (all P>0.05). Western blotting results showed that the protein expression levels of PRRX1 and SP7 in the ML141-treated group had no significant differences with the control group. Live cell imaging showed that compared with the control group [(31.42±4.01)%], the proportion of TNTs and mitochondrial transfer in the ML141-treated groups [(13.45±1.46)%, (10.36±3.47)%, (9.32±1.11)%] were significantly decreased in dental MSCs (all P<0.001). Scanning electron microscope showed that the mitochondrial morphology of dental MSCs in the ML141-treated group was similar to the control group, with globular and short-rod shape. After 7 days of odontogenic differentiation, the ALP staining intensity of the ML141-treated group was significantly lower than the control group. After 21 days of induction, RT-qPCR results showed that compared with control group, the relative mRNA expressions of Alp, Sp7, Dmp1 and Dspp were significantly decreased in the ML141-treated group (all P<0.05), indicating that the suppression of mitochondrial transfer in dental MSCs inhibited the odontogenic differentiation. Conclusions:Mitochondrial transfer exists between dental MSCs, and inhibition of mitochondrial transfer impairs the odontogenic differentiation.

Hearing loss is the most prevalent disabling disease. Cochlear implantation（CI） serves as the primary intervention for severe to profound hearing loss. This consensus systematically explores the value of genetic diagnosis in the pre-operative assessment and efficacy prognosis for CI. Drawing upon domestic and international research and clinical experience, it proposes an evidence-based medicine three-tiered prognostic classification system（Favorable, Marginal, Poor）. The consensus focuses on common hereditary non-syndromic hearing loss（such as that caused by mutations in genes like GJB2, SLC26A4, OTOF, LOXHD1） and syndromic hereditary hearing loss（such as Jervell & Lange-Nielsen syndrome and Waardenburg syndrome）, which are closely associated with congenital hearing loss, analyzing the impact of their pathological mechanisms on CI outcomes. The consensus provides recommendations based on multiple round of expert discussion and voting. It emphasizes that genetic diagnosis can optimize patient selection, predict prognosis, guide post-operative rehabilitation, offer stratified management strategies for patients with different genotypes, and advance the application of precision medicine in the field of CI.
Humans ; Cochlear Implantation ; Prognosis ; Hearing Loss/surgery* ; Consensus ; Connexin 26 ; Mutation ; Sulfate Transporters ; Connexins/genetics*

BACKGROUND:Currently,the mandibular joint prosthesis manufactured at home and abroad needs to rely on screws to fix the condylar part of the prosthesis during the replacement process,and the retention hole is reserved to facilitate the operation during the operation.However,due to the lack of personalized jaw design,the reattachment plate may not fit the jaw,resulting in screw loosening and dislocation.Therefore,personalized condylar prosthesis replacement is of great value in the repair of the temporomandibular joint.OBJECTIVE:To design a personalized condylar prosthesis with an internal GYROID for mandibular condylar repair and reconstruction.METHODS:The GYROID structure was selected in the Rhinoceros 7 software with the single cell size of 6 mm and the wall thickness of 0.2,0.3,0.4,0.5,0.6,0.7,0.8 mm.The mechanical properties of the GYROID structure were analyzed by finite element method.3D printing of GYROID structural test specimens with different wall thickness(0.2,0.3,0.4,0.5,0.6,0.7,and 0.8 mm)was performed to test the mechanical properties of the specimens through room temperature compression experiments.A wall thickness value conforming to the range of mandibular mechanical properties was selected through finite element analysis and room temperature compression test results.An adult male mandibular CT data were used for inverse modeling to design a condylar prosthesis with an internal GYROID.Finite element analysis was used to simulate the movement of the apical staggered position and the opposite-blade jaw position after condylar prosthesis replacement.RESULTS AND CONCLUSION:(1)The results of finite element analysis and room temperature compression experiment showed that the elastic modulus of the GYROID structure increased with the increase of wall thickness.The elastic modulus of the GYROID structure with wall thickness of 0.5-0.7 mm was within the range of the elastic modulus of the mandible(1.5-4.0 GPa).Therefore,the 6 mm monocellular GYROID structural model with a wall thickness of 0.6 mm was selected for the design of the condylar prosthesis.(2)The results of finite element analysis showed that the stress distribution of mandibular model was symmetrical.The stress distribution of the two types of occlusion was roughly the same,and the stress peak was not significantly different.The stress concentrated in the neck of the condylar prosthesis,and the stress on the replacement side was slightly larger than that on the healthy side.The maximum equivalent stress of the whole internal fixation model was 269.34 MPa,and the maximum equivalent stress of the screw was 20.14 MPa.The equivalent stress and equivalent strain values of the prosthesis were greater than that of the opposite edge jaw position when the tooth tip was interlaced.The equivalent stress and equivalent strain values of the screw were smaller than that of the opposite edge jaw position when the tooth tip was interlaced.(3)The results showed that the design and retention of the personalized GYROID condylar prosthesis were good,which was consistent with the mechanical conduction of the mandible.

BACKGROUND:Porous structures based on triple periodic minimal surfaces are one of the most promising orthopedic biostructures,among which the Gyroid structure is characterized by high specific surface area,high permeability,and zero mean curvature.OBJECTIVE:To screen the wall thickness interval of TC4 bionic bone scaffolds with 4 mm single-cell Gyroid structure matching the elastic modulus range of cancellous bone of the mandible through finite element analysis combined with mechanical compression test testing.METHODS:The finite element model of the 4 mm single-cell Gyroid structure with different wall thickths(0.1,0.2,0.3,0.4,0.5,0.6,0.7,and 0.8 mm)was established.The equivalent elastic modulus of the Gyroid structure was analyzed,and the wall thickness interval of the Gyroid structure matching the elastic modulus range of the maxillary resinous bone was selected with different wall thicknesses of 0.2,0.3,0.4,0.5,0.6,and 0.7 mm,respectively.According to finite element analysis screening results,the material selected was Ti6Al4V.Selective laser melting was used to prepare 3D printed Gyroid structure specimens.The surface treatment was carried out by large-grained sand blasting and acid etching.The elastic modulus and compressive strength of the specimen were tested by mechanical compression experiment.RESULTS AND CONCLUSION:(1)The finite element analysis results showed that the equivalent elastic modulus of the Gyroid structure increased with the increase of wall thickness,and the equivalent elastic modulus of the Gyroid structure with wall thickness of 0.2-0.7 mm was within the range of the elastic modulus of the spongy bone of the mandible(1.5-4.0 GPa),which was used for 3D printing of the Gyroid structure specimen.(2)The mechanical compression test results showed that the elastic modulus and compressive strength of the Gyroid structural specimen increased with the increase of wall thickness,and the elastic modulus of the Gyroid structural specimen with wall thickness of 0.3-0.5 mm was within the range of the elastic modulus of the cancellous bone of the mandible.The compressive strength of the Gyroid specimen with 0.3-0.7 mm wall thickness was consistent with the mechanical properties of the mandible.(3)The results show that the Gyroid structure of 0.3-0.5 mm wall thickness is compatible with the range of elastic modulus of the mandible.