Fatigue analysis of restored teeth longitudinally cracked under cyclic loading

ObjectiveTo investigate the fatigue behavior of restored teeth, in particular the mechanisms of longitudinal dentinal cracking under cyclic mechanical loading, using finite element analysis (FEA) and the stress-life (S-N) approach.MethodsTen root-filled premolars restored with resin composites were subjected to step-stress cyclic loading to produce longitudinal cracks. Fracture loads and number of cycles completed at each load level were recorded. FEA was used to predict the stress amplitude of each component under the global cyclic load. Both intact and debonded conditions were considered for the dentin-composite interface in the FEA. The predicted stress concentrations were compared with the fracture patterns to help elucidate the failure mechanisms. The S-N approach was further used to predict the lifetimes of the different components in the restored teeth. Cumulative fatigue damage was represented by the sum of the fractions of life spent under the different stress amplitudes.ResultsLongitudinal cracks were seen in ~50% of the samples with a mean fracture load of 770 ± 45 N and a mean number of cycles to failure of 32,297 ± 12,624. The longitudinal dentinal cracks seemed to start near the line angle of the cavity, and propagated longitudinally towards the root. The sum of fractions of life spent for the dentin-composite interface exceeded 1 after ~7000 cycles when that for dentin was much lower than 1, indicating that interfacial debonding would occur prior to dentin fracture. This was supported by micro-CT images showing widened interfacial space in the cracked samples. In the debonded tooth, FEA showed dentinal stress concentrations at the gingival wall of the cavity, which coincided with the longitudinal cracks found in the cyclic loading test. The sum of fractions of life spent for dentin was close to 1 at ~30,000 cycles, similar to the experimental value.SignificanceDebonding of the dentin-composite interface may occur prior to longitudinal cracking of dentin in root-filled teeth under cyclic loading. The approximate time of occurrence for these events could be estimated using fatigue analysis with stresses provided by FEA. This methodology can therefore be used to evaluate the longevity of restoration designs for root-filled teeth.     

Brilliance型16排螺旋CT的故障分析与维修

针对日常使用中遇到的Brilliance 16排螺旋CT高压系统、机架以及控制器局域网络(CAN)通讯等故障现象进行分析与维修,最终通过更换滤波电容、机架数据采集控制器(DMC)电源以及信号刷等配件得以排除故障。通过对故障准确判断以及合理运用厂家Service模式下的维修工具软件快速解决故障,保障了影像科检查工作的顺利进行,从而提高设备的稳定性。     

Effect of orbital wall resection areas in the treatment of patients with endocrine orbitopathy

In patients treated by orbital wall decompression for endocrine orbitopathy (EO) there is limited evidence on the effect of orbital wall resections. Thus, the aim of this study was to evaluate the effect of one, two, and three-wall resections on orbital parameters to determine if any such correlations exist. Preoperative and postoperative data from all patients at a tertiary care centre who underwent decompression surgery from 2010 - 2020 were digitally analysed. The effect of the number and area of resected walls on orbital area, orbital volume, and Hertel value, and the effect of lateral rim advancement (LARA) were determined. A total of 131 orbital areas showed an increase from a mean (SD) preoperative area of 42.0 (4.6) cm² to 47.3 (6.1) cm² postoperatively (p<0.001). In total, the mean (SD) area of osseous wall removed in all patients was 6.2 (1.7) cm² at the lateral orbit (n = 129), 6.7 (2.3) cm² at the orbital floor (n = 123), and 5.8 (1.8) cm² at the medial orbital wall (n =30). The mean (SD) orbital volume increased by 6.0 (3.0) cm³ after decompression. There was also a significant reduction in exophthalmos of 7.3 (3.2) mm (from 25.2 (3.9) to 17.9 (3.5), p<0.001). LARA was performed in 50 patients. Changes in volume and area, and reduction in exophthalmos were not significantly different with or without LARA. The postoperative effects of orbital wall resection are predictable and exhibit a relation with six units of change. Two-wall resection is the most common intervention.     

Contemporary Management of Ischemic Mitral Regurgitation at Coronary Artery Bypass Grafting

BackgroundRecent guidelines for the treatment of moderate or severe ischemic mitral regurgitation (IMR) in patients undergoing coronary artery bypass grafting (CABG) have changed. This study assessed the real-world impact of changing guidelines on the management of IMR during CABG over time. We hypothesized that the utilization of mitral valve repair for IMR would decrease over time, whereas mitral valve replacement for severe IMR would increase.MethodsPatients undergoing CABG in a statewide collaborative database (2011-2020) were stratified by severity of IMR. Trends in mitral valve repair or replacement were evaluated. To account for differences of the patients, propensity score–matched analyses were used to compare patients with and without mitral intervention.ResultsA total of 11,676 patients met inclusion criteria, including 1355 (11.6%) with moderate IMR and 390 (3.3%) with severe IMR. The proportion of patients undergoing mitral intervention for moderate IMR decreased over time (2011, 17.7%; 2020, 7.5%; P_trend = .001), whereas mitral replacement for severe IMR remained stable (2011, 11.1%; 2020, 13.3%; P_trend = .14). Major morbidity was higher for patients with moderate IMR who underwent mitral intervention (29.1% vs 19.9%; P = .005). In a propensity analysis of 249 well-matched pairs, there was no difference in major morbidity (29.3% with mitral intervention vs 23.7% without; P = .16) or operative mortality (1.2% vs 2.4%; P = .5).ConclusionsConsistent with recent guideline updates, patients with moderate IMR were less likely to undergo mitral repair. However, the rate of replacement for severe IMR did not change. Mitral intervention during CABG did not increase operative mortality or morbidity.     

Dietary patterns and the risk of abnormal blood lipids among young adults: A prospective cohort study

Background and aimsThe extent to which dietary patterns influence the risk of abnormal blood lipids throughout young adulthood remains unclear. The aim was to investigate whether early young adulthood dietary patterns predict the risk of abnormal blood lipids during later young adulthood.Methods and resultsWe used data from a long running birth cohort study in Australia. Western dietary pattern rich in meats, processed foods and high-fat dairy products and prudent pattern rich in fruit, vegetables, fish, nuts, whole grains and low-fat dairy products were derived using principal component analysis at the 21-year follow-up from dietary data obtained using a food frequency questionnaire. After 9-years, fasting blood samples of all participants were collected and their total, low-density lipoprotein (LDL) and high-density lipoprotein (HDL) cholesterols and triglyceride (TG) levels were measured. Abnormal blood lipids were based on clinical cut-offs for total, LDL and HDL cholesterols, and TG and relative distributions for total:HDL and TG:HDL cholesterols ratios. Log-binomial models were used to estimate risk of each outcome in relation to dietary patterns. Greater adherence to the Western pattern predicted increased risks of high LDL (RR: 1.47; 95%CI: 1.06, 2.03) and TG (1.90; 1.25, 2.86), and high ratios of total:HDL (1.48; 1.00, 2.19) and TG:HDL (1.78; 1.18, 2.70) cholesterols in fully adjusted models. Conversely, a prudent pattern predicted reduced risks of low HDL (0.58; 0.42, 0.78) and high TG (0.66; 0.47, 0.92) and high total:HDL (0.71; 0.51, 0.98) and TG:HDL (0.61; 0.45, 0.84) cholesterols ratios.ConclusionThis is the first prospective study to show greater adherence to unhealthy Western diet predicted increased risks of abnormal blood lipids, whereas healthy prudent diet predicted lower such risks in young adults. Addressing diets in early course may improve cardiovascular health of young adults.     

基于DEA方法的华法林抗凝分级管理模式的效率评价

目的:通过小范围的临床实践,使用数据包络分析(data envelopment analysis,DEA)方法对基于全程化抗栓药学服务模式的华法林抗凝管理工作效率进行评价。方法:选取2021年7-12月南京大学医学院附属鼓楼医院心胸外科瓣膜置换术后使用华法林抗凝的患者。将患者分为实验组和对照组,实验组由临床药师利用基于分级管理的全程化抗栓药学服务模式进行抗凝管理和药学监护,对照组由临床药师按照无差别监护模式进行抗凝管理和监护,记录2种模式下药师工作内容和工作成效,通过DEA方法分析比较2种抗凝管理模式的效率。结果:研究最终纳入服用华法林的患者233人(实验组116人,对照组117人),实验组的单位患者管理时间显著减少[(27.8±9.7)min vs.(34.8±11.4)min]。经模型计算后,实验组的总体效率值为1,说明其投入和产出最优,且效率高于对照组。结论:全程化抗栓药学服务模式下药师管理单位抗凝患者需要的时间更少,管理效率更高。     

Policy Analysis for Prevention and Control of Influenza in Aged Care

ObjectiveThis study aimed to analyze national influenza infection control policy documents within aged care settings by identifying the consistencies, inconsistencies, and gaps with the current evidence and by evaluating methodological quality. Aged care providers can use these findings to identify their policy documents' strengths and weaknesses.DesignA quality and content analysis of national level policy documents.Setting and ParticipantsAged care settings rely on national agencies' policy recommendations to control and prevent outbreaks. There is limited research on the effectiveness of control measures to prevent and treat influenza within aged care settings. Because of the complexities around aged care governance, the primary responsibility in developing a comprehensive facility-level, infection-prevention policy, falls to the providers.MethodsThe analysis was conducted using the (1) International Appraisal of Guidelines, Research and Evaluation assessment tool, containing 23 items across 6 domains; and the (2) Influenza Related Control Measures in Aged Care settings checklist, developed by the authors, with 82 recommendations covering: medical interventions, nonmedical interventions, and physical layout.ResultsThere were 19 documents from 9 different high-income countries, with a moderately high methodological quality in general. The quality assessment's average score was 40.2% (95% CI 31.9%–44.7%). “Stakeholder involvement” ranked third, and “Editorial independence” and “Rigor of development” had the lowest average scores across all domains. The content analysis' average score was 37.2% (95% CI 10.5%–21.5%). The highest scoring document (59.1%) included term definitions, cited evidence for recommendations, and clear measurable instructions. “Physical Layout” had the least coverage and averaged 21.9% (95% CI 4.2%–37.5%), which shows a substantial gap in built environment recommendations.Conclusions and ImplicationsExisting policy documents vary in their comprehensiveness. The higher scoring documents provide an ideal model for providers. The checklist tools can be used to assess and enhance documents. Further research on document end-user evaluation would be useful, as there is room for improvement in methodological quality and coverage of recommendation coverage, especially related to physical layout.     

Reliability and validity of the gait classification system in children with cerebral palsy (GCS-CP)

BackgroundGait classification systems (GCS) may enable clinicians to differentiate gait patterns into clinically significant categories that assist in clinical decision-making and assessment of outcomes. Davids and Bagley in 2014 [1] described a GCS for children with cerebral palsy (GCS-CP). The purpose of our study was to use the GCS-CP for the first time on a sample of patients with CP and to evaluate the reliability and utility of the classification system.MethodsThe gait of 131 children with CP was retrospectively reviewed and classified according to Davids and Bagley’s classification using two-dimensional (2D) video and three-dimensional (3D) lower limb kinematics and kinetics. Gross Motor Function Classification System (GMFCS) levels were determined, and the Gait Profile Scores (GPS) calculated to characterize the sample concerning gait classification. The comparison between the groups was performed using the Kruskal-Wallis test with respect to the non-normal distribution of the data. The intrarater and interrater reliability was determined using the Kappa index (k) statistics with 95% CI.ResultsAll GCS-CP groups were represented within the evaluated sample. Of the 131 cases evaluated, 127 (96.95%) were able to be classified with respect to sagittal plane stance phase gait deviations. All patients in the sample were able to be classified with respect to sagittal plane swing phase and transverse plane gait deviations. The interrater reliability was 0.596 and 0.485 for the first and second levels of the classification, respectively, according to the Fleiss’s Kappa statistics. Intrarater reliability was 0.776 and 0.714 for the raters one and two, respectively, according to the Cohen’s Kappa statistics.SignificanceThe GCS-CP exhibited clinical utility, successfully classifying almost all subjects with CP in two planes, based upon kinematic and kinetic data. The classification is valid and has moderate interrater and moderate to substantial intrarater reliability.     

不同针灸疗法治疗寻常痤疮的网状Meta分析＊

目的 采用网状Meta分析方法，评价针刺、火针、艾灸等不同针灸疗法对寻常痤疮（acne vulgaris， AC）临床有效率及复发率的影响。方法 计算机检索PubMed、Embase、Cochrane、Web of Science、CINAHL、中国知网（China National Knowledge Infrastructure， CNKI）、万方数据库（WanFang Data）、中国生物医学文献数据库（China Biology Medicine disc， CBM）和维普中文期刊服务平台（VIP Database），搜集针灸疗法治疗寻常痤疮的随机对照试验（randomized controlled trail， RCT），检索时间均为建库至2021年3月，文献筛选、资料提取及偏倚风险评价均由两名研究者独立进行。数据分析使用Stata16.0软件。结果 纳入42项RCT，共3911例寻常痤疮患者。数据分析结果显示，临床总有效率：艾灸、放血、放血+穴位注射、放血+针刺、火针优于西药（P<0.05），放血、放血+穴位注射、放血+针刺、火针、穴位埋线优于针刺疗法（P<0.05），放血+针刺疗法优于自血疗法（P<0.05），累计排序概率曲线下面积（surface under the cumulative，SUCRA）显示放血+针刺治疗寻常痤疮总有效率最高；复发率：放血疗法+穴位注射优于电针（P<0.05），SUCRA结果显示针刺+自血疗法治疗寻常痤疮复发率最低。结论 放血联合针刺疗法在提高总有效率上具有最好的疗效，针刺联合自血疗法可有效降低复发率，受纳入研究所限，以上结论尚需更多大样本、高质量RCT进一步验证。