BACKGROUND:One of the advantages of clear aligner treatment is molar distalization.However,tooth tilting movement and loss of anterior anchorage may occur during treatment.There are few studies on whether these problems can be improved by selecting clear aligners with different thicknesses and edges to improve the clinical treatment effect.OBJECTIVE:To analyze the control ability of clear aligners with different thickness and edges on the central incisor,lateral incisor,and second molar when pushing the maxillary second molar distally by three-dimensional finite element analysis.METHODS:Three-dimensional finite element analysis models of bilateral maxillary second molar distalization with clear aligner,maxillary dentition,periodontal ligament,and alveolar bone with different thicknesses and margins were established by Mimics,Geomagic Wrap,3-matic and SolidWorks software,respectively.There were 16 combinations of four thicknesses(0.4,0.5,0.625,and 0.75 mm)and four margins(scallop,straight,straight extension 2 mm and straight extension 4 mm).The data were imported into Ansys Workbench software for design and solution.The mean value,peak value and distribution of the periodontal ligament equivalent stress of the second molar,the equivalent stress and the maximum initial displacement of the second molar,and the control ability of each appliance on the second molar,central incisor,and lateral incisor were analyzed.RESULTS AND CONCLUSION:(1)The mean equivalent stress of periodontal ligament of the second molar,the equivalent stress of the second molar and the maximum initial displacement of the second molar increased with the extension of the appliance edge and the increase of the thickness of the appliance in the 16 groups of models.(2)When the thickness of appliances was the same,the maximum equivalent stress of the second molar in the linear appliance group was the highest,and the maximum equivalent stress of the second molar in the linear extended appliance group was greater than that in the scallop appliance group.When the edge of the appliance was the same,the periodontal ligament equivalent stress peak of the second molar increased with the increase of the thickness of the appliance.The equivalent stress distribution in the periodontal ligament of the second molar in the linear extendable appliance group was more uniform than that in the scallop appliance group and the linear appliance group.(3)When the thickness of the appliance was the same,the scallop-shaped appliance had the worst control on the second molar.When the edge of the appliance was the same,with the increase of the thickness of the appliance,the control of the second molar by the linear extender appliance was gradually stronger than that by the linear appliance.The control of the central incisor was stronger and more stable with the linear extended 2 mm appliance,while the control of the lateral incisor was stronger and more stable with the linear appliance.(4)The results showed that when using clear aligners to push molars distally,extending the edge of the appliance could improve the control of the molars and reduce the tilting movement of the teeth.The design of a straight extension margin of 2 mm for the central incisor and a straight edge for the lateral incisor can enhance the control of the anchorage incisor and reduce the labial inclination of the anterior teeth.

BACKGROUND:One of the advantages of clear aligner treatment is molar distalization.However,tooth tilting movement and loss of anterior anchorage may occur during treatment.There are few studies on whether these problems can be improved by selecting clear aligners with different thicknesses and edges to improve the clinical treatment effect.OBJECTIVE:To analyze the control ability of clear aligners with different thickness and edges on the central incisor,lateral incisor,and second molar when pushing the maxillary second molar distally by three-dimensional finite element analysis.METHODS:Three-dimensional finite element analysis models of bilateral maxillary second molar distalization with clear aligner,maxillary dentition,periodontal ligament,and alveolar bone with different thicknesses and margins were established by Mimics,Geomagic Wrap,3-matic and SolidWorks software,respectively.There were 16 combinations of four thicknesses(0.4,0.5,0.625,and 0.75 mm)and four margins(scallop,straight,straight extension 2 mm and straight extension 4 mm).The data were imported into Ansys Workbench software for design and solution.The mean value,peak value and distribution of the periodontal ligament equivalent stress of the second molar,the equivalent stress and the maximum initial displacement of the second molar,and the control ability of each appliance on the second molar,central incisor,and lateral incisor were analyzed.RESULTS AND CONCLUSION:(1)The mean equivalent stress of periodontal ligament of the second molar,the equivalent stress of the second molar and the maximum initial displacement of the second molar increased with the extension of the appliance edge and the increase of the thickness of the appliance in the 16 groups of models.(2)When the thickness of appliances was the same,the maximum equivalent stress of the second molar in the linear appliance group was the highest,and the maximum equivalent stress of the second molar in the linear extended appliance group was greater than that in the scallop appliance group.When the edge of the appliance was the same,the periodontal ligament equivalent stress peak of the second molar increased with the increase of the thickness of the appliance.The equivalent stress distribution in the periodontal ligament of the second molar in the linear extendable appliance group was more uniform than that in the scallop appliance group and the linear appliance group.(3)When the thickness of the appliance was the same,the scallop-shaped appliance had the worst control on the second molar.When the edge of the appliance was the same,with the increase of the thickness of the appliance,the control of the second molar by the linear extender appliance was gradually stronger than that by the linear appliance.The control of the central incisor was stronger and more stable with the linear extended 2 mm appliance,while the control of the lateral incisor was stronger and more stable with the linear appliance.(4)The results showed that when using clear aligners to push molars distally,extending the edge of the appliance could improve the control of the molars and reduce the tilting movement of the teeth.The design of a straight extension margin of 2 mm for the central incisor and a straight edge for the lateral incisor can enhance the control of the anchorage incisor and reduce the labial inclination of the anterior teeth.

Interventional therapy promises a novel treatment for muscle invasive bladder cancer(MIBC),but the long-term effect is limited,and combination therapy is necessary for MIBC.Cryoablation kills tumors by freezing tissue with ultra-low temperature,but its safety and efficacy for MIBC remains unclear.The research progresses in cryoablation for bladder cancer animal models and human MIBC were reviewed in this article.

Objective:To investigate the incidence, risk factors, and outcomes of falls among the elderly community population in Beijing.Methods:A cross-sectional survey was conducted using stratified multistage random sampling to select urban and rural residents aged 65 years and older in Beijing. Mortality data was collected after the baseline survey for 5 years. The incidence of falls was weighted based on the composition ratios of age and gender from the 2010 Nation-wide Population Census of Beijing. A logistic regression model was used to analyze the impacts of demographic sociology of common chronic diseases on fall occurrence. The Cox proportional hazards regression model was used to analyze the fall and 5-year survival association.Results:A total of 2 968 participants completed the questionnaire, at cross-sectional survey, with an average age of (73.2±6.0) years, and 1 581 (53.8%) participants were female. Three hundred and sixty-one individuals experienced a fall within the past year. Among those who fell, 64 (17.7%) fell twice, and 95 (26.6%) fell three or more times. Of them, 14.4% (52) had post-fall fractures, with the wrist, knee, and hip being the most common fracture sites, accounting for 25.0%, 17.3%, and 15.4%, respectively. The weighted fall incidence was 12.4% (95% CI: 11.2%-13.5%). Aging, being female, and living in rural areas were more likely to fall. Logistic regression analysis showed that after adjusting for age, gender, and urban-rural status, the risk of falls for those living alone ( OR=1.48, 95% CI: 1.08-2.04) or living with children/grandchildren ( OR=1.51, 95% CI: 1.15-1.97) were significantly higher than those living with their spouse. In addition, the risk of falls was elevated significantly among the elderly with hypertension, diabetes, stroke, dementia, depression status, urinary incontinence, arthritis, insomnia, vision, and hearing loss, dependence on activities of daily living (ADL), general and poor self-rated health (SRH). The Cox proportional hazard regression model revealed that the 5-year risk of death increased by 65% ( HR=1.65, 95% CI: 1.29-2.11) for those who experienced a fall, which increased with fall frequency. This elevated risk persisted after adjusting for chronic conditions, ADL, and SRH. Conclusions:Ageing, female, living in rural regions, having common chronic diseases, dependence on ADL, general and poor SRH, living alone or living with children/grandchildren were associated with the elevated fall risk. The occurrence of fall was seasonal. The most common short-term adverse consequence after a fall was fractures, while the long-term effect was an increased risk of death.

Objective:To evaluate the clinical efficacy of a novel reduction device in the treatment of A3N0/1 thoracolumbar fracture using navigation-assisted techniques.Methods:A retrospective analysis was conducted on 45 patients (29 males, 16 females; mean age 40.67±16.11 years, range 24-57) with thoracolumbar fractures who underwent fracture reduction and pedicle screw fixation via the Wiltse approach at Zhengzhou Orthopaedic Hospital between January 2022 and January 2023. Injury levels included: T 10 in 2 cases, T 11 in 5 cases, T 12 in 13 cases, L 1 in 20 cases, L 2 in 3 cases, L 3 in 2 cases. All patients underwent fracture reduction via the Wiltse approach using the spinal fracture reduction instrument for vertebral body reduction. Among them, 20 patients received O-arm navigation-assisted internal fixation and vertebral reduction (O-arm group), while 25 received C-arm fluoroscopy-guided internal fixation and vertebral reduction (C-arm group). Operative time, intraoperative blood loss, vertebral reduction time using the instrument, first-time screw placement success rate, screw placement accuracy, and complications were compared. Mid-vertebral body height ratio (MVBHr), local Cobb angle of the fractured vertebra, visual analogue scale (VAS) score, and Oswestry disability index (ODI) were compared preoperatively, at 1 week postoperatively, 3 months postoperatively, and final follow-up. Results:All surgeries were successfully completed in both groups. Operative time was significantly shorter in the O-arm group (106.8±14.4 min) than in the C-arm group (119.1±16.4 min, P<0.05). All patients were followed up for a mean duration of 15.9±3.9 months (range 12-20 months). Vertebral reduction time was significantly shorter in the O-arm group (11.0±2.2 min) than in the C-arm group (20.4±5.7 min, P<0.05). The first-time screw placement success rate was significantly higher in the O-arm group (100%) than in the C-arm group (95.3%, P<0.05). Screw placement accuracy (Grade I) was significantly higher in the O-arm group (117 screws, 97.5%) than in the C-arm group (136 screws, 90.7%, P<0.05). No cases of wrong-level surgery, infection, or spinal cord/nerve injury occurred. Both groups showed significant improvements in MVBHr, Cobb angle, VAS, and ODI at all postoperative time points compared to preoperative values ( P<0.05). At final follow-up, the O-arm group demonstrated significantly better outcomes than the C-arm group in MVBHr (90.6%±4.5% vs. 86.4%±6.9%, P<0.05), Cobb angle (7.6°±1.8° vs. 10.1°±3.2°, P<0.05), VAS (1.3±0.4 vs. 1.7±0.6, P<0.05), and ODI (4.6%±1.9% vs. 7.7%±2.0%, P<0.01). Conclusion:O-arm navigation-assisted intrasegmental push reduction for A3N0/1 type thoracolumbar fractures demonstrates advantages including faster and more accurate screw placement, precise reduction with improved outcomes, and significant postoperative pain relief.

OBJECTIVE To investigate the management status of small pressure steam sterilizers in dental institu-tions across seven major regions of China and provide references for establishing standardized monitoring and eval-uation protocols for sterilization efficacy.METHODS From Aug.to Nov.2023,a convenience sampling method was employed to select 885 dental institutions of various levels from seven geographical regions.An online survey using a self-designed questionnaire was conducted to assess the management status of small pressure steam steri-lizers in dental institutions.RESULTS A total of 885 questionnaires were distributed,with 770 valid responses col-lected,covering 770 dental institutions at all levels.The survey involved 2 056 small pressure steam sterilizers,of which 43.14％were pre-vacuum type and 89.40％were benchtop models.Tertiary dental institutions had the high-est proportion of imported small pressure steam sterilizers(60.15％),with most devices in use for 5-10 years(36.88％).Secondary and low er-level institutions predominantly used domestically produced small pressure steam sterilizers(74.60％),which used for 3-5 years accounting for the highest proportion(34.29％).While 85.58％of dental institutions employed dedicated sterilization personnel,only 45.84％performed proper maintenance for small pressure steam sterilizers.Training rates were 80.00％for department of stomatology in ungraded general hospitals and primary medical institutions,76.19％in prejob and 71.43％during the work for department of sto-matology in primary clinics,respectively.CONCLUSIONS Although most dental institutions demonstrate sound policy formulation,challenges persist in equipment maintenance,policy implementation and grassroots training.Future efforts should be made on strengthening maintenance and inspection of equipment,enhancing sys-tem supervisory mechanisms,and optimizing training systems to ensure dental treatment safety.

In proton therapy,prompt gamma-ray imaging is considered as one of the most promising methods for assessing proton beam range.Prompt gamma-ray imaging detector evaluates the proton beam range based on the prompt gamma-ray distribution obtained by the prompt gamma-ray imaging system,which enables high-precision measurement of the proton beam range.Herein a proton beam range verification algorithm is designed for the newly developed prototype of the range verification detector(pixelated prompt gamma-ray imaging detector),which verifies the range estimation accuracy of the prototype for different phantoms and different energies of homogeneous media through Monte Carlo simulation.The results show that the accuracy of the proton beam range verification algorithm is within 0.5 mm of the safety margin error of the Bragg peak,and the measurement accuracy is significantly improved with the increase of the number of protons,indicating that the prototype algorithm is feasible for proton beam range verification.

Objective To assess the therapeutic effects of ultrasound(US)assisted administration of nusinersen in spinal muscular atrophy(SMA)patients with scoliosis.Methods The clinical data of 7 SMA patients with scoliosis treated with US assisted administration of nusinersen were retrospectively reviewed.The locating time,level of puncture points,puncture time,the number of puncture attempts,pain scores and adverse events were recorded.Meantime,the learning curve(LC)of US assisted administration of nusinersen for SMA patients with scoliosis was analyzed using cumulative sum(CUSUM).Results Thirty-one procedures were performed on 7 SMA patients with scoliosis.The success rate was 100％.The locating time was 11.9(5.1,15.4)min,the puncture time was 12.6(6.0,16.9)min,the number of puncture attempts were 2.0(1.0,3.0),the pain scores were 2.1(1.0,3.0).During the follow-up period of six months,only 1 patient had dizziness and soreness of waist.No serious adverse events were observed.The locating time,puncture time and the number of puncture attempts decreased as the number of procedures increased.Evaluation of the CUSUM curve revealed that 14 cases were needed to achieve proficiency.Conclusion US assisted administration of nusinersen is a valid and safe technique,deserving further clinical promotion and application on SMA patients with scoliosis.

In proton therapy,prompt gamma-ray imaging is considered as one of the most promising methods for assessing proton beam range.Prompt gamma-ray imaging detector evaluates the proton beam range based on the prompt gamma-ray distribution obtained by the prompt gamma-ray imaging system,which enables high-precision measurement of the proton beam range.Herein a proton beam range verification algorithm is designed for the newly developed prototype of the range verification detector(pixelated prompt gamma-ray imaging detector),which verifies the range estimation accuracy of the prototype for different phantoms and different energies of homogeneous media through Monte Carlo simulation.The results show that the accuracy of the proton beam range verification algorithm is within 0.5 mm of the safety margin error of the Bragg peak,and the measurement accuracy is significantly improved with the increase of the number of protons,indicating that the prototype algorithm is feasible for proton beam range verification.

Objective:To analyze the association between healthcare workers mental health,institu-tional supplies and facilities,inter-organizational coordination during infectious disease outbreaks,and the healthcare institution resilience.Methods:An online questionnaire survey was conducted among the healthcare workforce from 146 institutions in Beijing from January 13,2023 to February 9,2023,and a total of 1 434 eligible respondents were included.The sample comprised 408 responses from tertiary hos-pitals,117 from secondary hospitals,and 909 from primary care institutions.The resilience indicator for healthcare institutions was defined as the degree to which medical services met patient demands,with in-fluencing factors including physical factors,such as material shortages and facility space adaptation or ex-pansion,organizational factors such as information sharing and patient referral,and psychological factors were evaluated using job satisfaction(extrinsic satisfaction,intrinsic satisfaction),burnout(emotional exhaustion,depersonalization,reduced personal accomplishment),and depression status.Ordered mul-ticlassification Logistic regression was used to examine the impact of various factors on the degree to which healthcare services met patient needs;additionally,demographic factors that might influence institutional resilience were controlled.Results:During the emergency response phase,93％of hospitals maintained the capacity to meet patient needs,though tertiary hospitals demonstrated significantly higher rates of service inadequacy(21.05％).Material shortages were reported across all institutions,with tertiary hos-pitals experiencing more frequent multi-item shortages.Inter-institutional collaboration patterns revealed substantial variation:87.50％of primary care facilities,42.86％of secondary hospitals,and 31.58％of tertiary hospitals.Healthcare workers across all levels reported mild depressive symptoms and moderate-to-severe burnout levels.Regression analysis showed high satisfaction(overall satisfaction β=0.04,ex-trinsic satisfaction β=0.06,and intrinsic satisfaction β=0.08),low degree of job burnout(emotional exhaustion β=-0.04,depersonalization β=-0.07 and reduced personal accomplishment β=0.01),low degree of depression(β=-0.06)were significantly associated with higher healthcare institution re-silience.In addition,material shortages were significantly associated with lower resilience,and renova-tion and expansion of treatment spaces,and information sharing,were all associated with higher resilience.Demographic factors(age,gender,marital status,educational background,etc.)had no sig-nificant impact on resilience.Conclusion:Mental health status significantly influences healthcare institu-tion resilience.As human resources constitute the core asset of healthcare institutions,strategic optimiza-tion of workforce allocation and psychological support interventions can effectively strengthen resilience.Moreover,healthcare institution resilience is positively impacted by orderly material supply chains,timely resource distribution,and adaptive reconfiguration of clinical spaces.Finally,facilitating information sharing also enhances institutional resilience.