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.     

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.     

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。     

Robust antibody response after a third BNT162b2 vaccine compared to the second among immunocompromised and healthy individuals,a prospective longitudinal cohort study

PurposeAs protection from COVID-19 following two doses of the BNT162b2 vaccine showed a time dependent waning, a third (booster) dose was administrated. This study aims to compare the antibody response following the third dose versus the second and to evaluate post-booster seroconversion.MethodsA prospective observational study conducted in Maccabi Healthcare Services. Serial SARS-CoV-2 Spike IgG tests, 1,2,3 and 6 months following the second vaccine dose and one month following the third were obtained. Neutralizing antibody levels were measured in a subset of participants. Per individual SARS-CoV-2 Spike IgG titer ratios were calculated one month after the booster administration compared to titers one month following the second dose and prior to booster.ResultsAmong 110 participants, 56 (51%) were women. Mean age was 61.7 ± 1.9 years and 66 (60%) were immunocompromised. One month after third dose, IgG titers were induced 7.83 (95 %CI 5.25–11.67) folds and 2.40 (95 %CI 1.90–3.03) folds compared to one month after the second, in the immunocompromised and immunocompetent groups, respectively. Of the 17 immunocompromised participants who were seronegative after the second dose, 4 (24%) became seropositive following the third. Comparing the titers prior to the third dose, an increase of 50.7 (95 %CI 32.5–79.1) fold in the immunocompromised group and 25.7 (95 %CI 19.1–34.7) fold in and immunocompetent group, was observed.ConclusionA third BNT162b2 vaccine elicited robust humoral response, superior to the response observed following the second, among immunocompetent and immunocompromised individuals.     

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.     

重组人表皮生长因子凝胶联合CO2点阵激光治疗增生性瘢痕的效果观察

目的观察重组人表皮生长因子凝胶联合CO₂点阵激光治疗烧伤及创伤后增生性瘢痕的临床效果。 方法选择2020年12月至2021年10月安徽医科大学第一附属医院烧伤与创面修复外科收治的20例增生性瘢痕患者，按照随机数字表法将患者分为联合治疗组及单纯激光治疗组，每组10例。术前均对2组患者术区进行拍照存像、消毒、擦干，局部均匀涂抹5%复方利多卡因乳膏后以无菌薄膜封闭保护60 min，擦去乳膏后再次消毒术区。术中使用CO₂点阵激光治疗仪对患者瘢痕部位进行扫描，根据患者增生性瘢痕厚度选定合适的机器参数，维持机器频率300 Hz及密度5%，在20～30 J调整能量参数的大小，时间间隔1 s，保证点阵矩形完全覆盖增生瘢痕，允许2次激光形成的热损伤矩阵之间存在25%面积的重叠。术后即刻冷敷创面60 min，冷敷结束至术后1周，单纯激光治疗组不外用任何药物，联合治疗组术区加用重组人表皮生长因子凝胶外用，3次/d。术后3 d治疗部位不碰水，若出现感染情况，可以加用抗生素软膏，点状损伤创面外痂皮未掉落完全时禁止擦洗创面，禁止直接剥除痂皮，禁止术区涂抹化妆品等，避免接受阳光直射。于第1次激光治疗后2个月进行第2次激光治疗，以2次CO₂点阵激光治疗为1个疗程，1个疗程治疗后间隔2个月待术区稳定后行疗效判断，计算2组患者治疗的总有效率；根据温哥华瘢痕量表(VSS)与患者与观察者瘢痕评估量表(POSAS)对患者治疗前、第1次激光治疗后2个月、第2次激光治疗后2个月瘢痕的各项指标进行评分。数据比较采用重复测量方差分析和χ²检验。 结果(1)治疗1个疗程后2个月，单纯激光治疗组与联合治疗组患者治疗的总有效率分别为80%(8/10)、90%(9/10)，2组间比较差异无统计学意义(χ²＝2.40，P＝0.49)。(2)对2组VSS评分的各项指标进行比较，其中疼痛、瘙痒、柔软度及厚度评分的组内及组间各时相点比较，差异均无统计学意义(P>0.05)。治疗前、第1次激光治疗后2个月及第2次激光治疗后2个月，单纯激光治疗组VSS评分中色泽评分分别为(1.9±0.7)、(1.9±0.1)、(1.8±1.0)分，联合治疗组分别为(2.9±0.7)、(2.8±0.6)、(1.9±0.7)分，2组在不同时相点组内比较，差异有统计学意义(F＝ 26.143，P<0.05)；2组组间不同时相点比较，差异有统计学意义(F＝6.753，P＝0.018)。治疗前、第1次激光治疗后2个月及第2次激光治疗后2个月，单纯激光治疗组VSS评分中血管分布评分分别为(1.8±1.0)、(1.7±0.7)、(1.5±1.0)分，联合治疗组分别为(2.6±0.5)、(2.5±0.5)、(1.7±0.8)分，2组在不同时相点组内比较，差异有统计学意义(F＝17.603，P<0.05)，2组组间不同时相点比较，差异无统计学意义(F＝ 2.538，P＝0.129)。(3)对2组POSAS评分的各项指标进行比较，其中厚度、粗糙度、柔软度和表面积评分的组内及组间各时相点比较，差异均无统计学意义(P>0.05)。治疗前、第1次激光治疗后2个月及第2次激光治疗后2个月，单纯激光治疗组POSAS评分中色泽评分分别为(4.9±2.6)、(4.1±0.8)、(3.5±2.0)分，联合治疗组分别为(7.6±1.1)、(6.8±1.4)、(5.4±1.8)分，2组在不同时相点组内比较，差异有统计学意义(F＝ 26.509，P<0.05)，2组组间不同时相点比较，差异有统计学意义(F＝ 8.973，P＝0.008)。治疗前、第1次激光治疗后2个月及第2次激光治疗后2个月，单纯激光治疗组POSAS评分中血管分布评分分别为(4.4±2.1)、(3.9±0.9)、(3.5±1.6)分，联合治疗组分别为(6.3±1.1)、(5.7±2.0)、(4.5±1.6)分，2组在不同时相点组内比较，差异有统计学意义(F＝ 20.118，P<0.05)，2组组间不同时相点比较，差异有统计学意义(F＝ 5.744，P＝0.028)。 结论重组人表皮生长因子凝胶联合CO₂点阵激光及单独使用CO₂点阵激光治疗增生性瘢痕均效果明确，但联合使用重组人表皮生长因子凝胶能有效促进创面愈合、改善瘢痕组织血管分布和减少局部色素沉着。