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.     

有限元法生物力学分析在青少年特发性脊柱侧凸治疗及病因研究中的应用

青少年特发性脊柱侧凸发病率较高且病情复杂,对青少年身心健康可造成显著影响,但其因病因不明,临床尚未形成治疗共识。近年来基于患者医学影像进行仿真建模的有限元法生物力学分析在青少年特发性脊柱侧凸治疗及其病因研究中已经有了一系列的应用。本文即从非手术治疗、手术治疗、病因研究、现有局限等角度对有限元法生物力学分析在青少年特发性脊柱侧凸中的应用进行综述,以期为临床实践及相关研究提供参考。     

注意缺陷多动障碍患儿血清25（OH）D及微量元素表达水平及临床意义

目的 探究注意缺陷多动障碍(ADHD)患儿血清25羟基维生素D[25(OH)D]、微量元素表达水平及临床意义。方法 选取2019年4月至2020年11月本院诊治的84例ADHD患儿进行研究(ADHD组),依据ADHD分型标准将患儿分为注意缺陷为主型组(28例)、多动为主型组(33例)、混合型组(23例),并选取同期84例体检健康儿童进行对照研究(对照组)。采用高效液相色谱-串联质谱法检测所有受试儿童血清25(OH)D水平；检测血清铁(Fe)、磷(P)、镁(Mg)、钙(Ca)、铜(Cu)、锌(Zn)、铅(Pb)水平；Pearson法分析ADHD患儿血清25(OH)D水平与Cu、Zn、Pb水平的相关性；Logistic回归分析ADHD发生的影响因素；受试者工作特征(ROC)曲线分析血清25(OH)D、Zn、Pb水平对ADHD的诊断价值。结果 ADHD组血清25(OH)D、Cu、Zn水平均显著低于对照组(P<0.05),Pb水平显著高于对照组(P<0.05)；注意缺陷为主型组、多动为主型组、混合型组患儿血清25(OH)D、Fe、P、Mg、Ca、Cu、Zn、Pb水平比较,差异无统计学意义(P>0.05)；ADHD患儿血清25(OH)D水平与Cu、Zn水平均呈正相关(P<0.05),与Pb水平呈负相关(P<0.05)；25(OH)D、Zn是影响ADHD发生的保护因素(P＜0.05),Pb是影响ADHD发生的危险因素(P＜0.05)；血清25(OH)D、Zn、Pb水平诊断ADHD的曲线下面积(AUC)分别为0.773、0.770、0.772,截断值分别为21.01 ng/mL、16.05 μmol/L、50.69 μg/L,相应灵敏度分别为82.1%、77.4%、63.1%,特异度分别为67.9%、71.4%、88.1%；三者联合诊断ADHD的AUC为0.883,其灵敏度、特异度分别为81.0%、81.0%。结论 ADHD患儿血清25(OH)D、Cu、Zn水平降低,Pb水平升高,25(OH)D、微量元素水平与ADHD患儿类型无关,25(OH)D、Zn、Pb联合有助于临床筛查ADHD患儿。     

特发性肺纤维化急性加重期证候与血清生物标志物的相关性研究＊

目的 通过分析特发性肺纤维化急性加重期（AE-IPF）患者证候与血清生物标志物的关系，为中医辨证治疗提供参考。方法 采用观察性研究设计，收集2019年3月至2019年11月三个中心的AE-IPF患者76例，其中痰热壅肺证26例、痰浊阻肺证50例，并纳入健康志愿者10例作为对照。采用ELISA测定患者血清CCL18、HMGB1、KL-6、MMP-7、SP-A和SP-D水平，分析与中医证候的相关性。结果 AE-IPF患者血清CCL18、HMGB1、KL-6、MMP-7、SP-A和SP-D水平均显著高于健康对照组。血清CCL18、HMGB1、KL-6、MMP-7和SP-D水平在痰热壅肺证和痰浊阻肺证患者间无显著性差异（P＞0.05），而血清SP-A水平存在显著性差异（P＜0.05）。结论 血清SP-A与AE-IPF证候存在一定的相关性，血清SP-A的浓度升高，与痰热壅肺证关系越密切，反之，血清SP-A浓度降低，则与痰浊阻肺证关系越密切。AE-IPF痰热壅肺证患者的预后可能较痰浊阻肺证患者更差。     

Serum uric acid in patients with ST-segment elevation myocardial infarction: An innocent bystander or leading actor?

Elevated serum uric acid (SUA) levels have been associated with several cardiovascular risk factors and the progression of coronary artery disease. In the setting of acute myocardial infarction, increasing evidence suggests that high SUA levels could be related to adverse outcomes. Interestingly elevated SUA levels have been linked to endothelial dysfunction, inflammation and oxidative stress. The aim of this review is to discuss the potential negative effects of SUA in patients with ST-segment elevation myocardial infarction undergoing primary percutaneous coronary intervention, analyzing the possible underlying pathophysiological mechanisms.     

Role of serum and synovial procalcitonin in differentiating septic from non-septic arthritis- a prospective study

IntroductionSeptic arthritis is a serious orthopaedic emergency that must be diagnosed and managed early to prevent devastating complications. The current gold standard for diagnosing septic arthritis is synovial fluid culture, but results are delayed by 48–72 h, and the sensitivity of the test is very low. Differentiating Septic from non-septic arthritis is vital to prevent unnecessary use of antibiotics and prevent complications. Serum Procalcitonin (PCT) is a useful marker in differentiating septic from non-septic arthritis but there are very few studies that have studied the role of synovial PCT for the same.AimTo determine the role of serum and synovial PCT in differentiating acute Septic from non-septic arthritis.Materials and methodsProspective clinical study in which 60 patients presenting with acute inflammatory arthritis (<2 weeks duration) were enrolled from May 2018 to May 2020. Serum and synovial fluid samples were drawn at presentation and routine blood investigations, synovial fluid culture sensitivity, and Procalcitonin levels were measured. Patients were divided into 3 groups, with group-1 having confirmed pyogenic, group-2 having presumed pyogenic, and group-3 having non –pyogenic patients, respectively. All data was tabulated and statistically analysed using appropriate tests.ResultsMean serum PCT values in groups 1, 2 and 3 were 1.06 ± 1.11, 0.85 ± 0.74, and 0.11 ± 0.24, respectively. Patients in the Pyogenic group (group1 and group 2) had significantly higher mean serum PCT as compared to group3 (p < 0.0001). Group 1 had higher serum PCT as compared to group 2, but the difference was not significant (p = 0.58). Mean synovial PCT in group 1, 2 and 3 were 2.42 ± 1.98, 1.89 ± 1.18, and 0.22 ± 0.40, respectively. Patients in the Pyogenic group (Group1 and Group2) had significantly higher mean synovial PCT as compared to Group 3 (p < 0.0001). Group 1 had higher mean synovial PCT as compared to group 2, but the difference was not significant (p = 0.54). The area under the ROC curve of the serum levels of PCT was 0.0.895, and the area under the ROC curve of the synovial fluid levels of PCT was 0.914, which was higher than the serum PCT level.ConclusionSerum and synovial Procalcitonin may be used as a diagnostic marker in differentiating septic from inflammatory arthritis and can help in reducing unnecessary use of antibiotics and early diagnosis and management of septic arthritis, thereby preventing complications.     

益气开秘方联合西药治疗便秘疗效及对患者血清5-HT、胃动素、血管活性肠肽水平的影响

目的:研究益气开秘方联合伊托必利及乳果糖对气阴两虚型便秘患者疗效及血清5-羟色胺(5-HT)、胃动素(MOT)、血管活性肠肽(VIP)水平的影响。方法:选择气阴两虚型便秘患者168例。依据随机数字表法将其分成观察组和对照组各84例,对照组应用伊托必利和乳果糖。观察组加用益气开秘方。两组均治疗4周,对比两组疗效,临床症状评分,血清5-HT、MOT及VIP水平及并发症。结果:观察组总有效率97.62%,较对照组89.29%明显更高(P<0.05)。治疗后两组临床症状评分均明显低于治疗前,且观察组较对照组明显降低(P<0.05)。治疗后两组血清5-HT及VIP水平均明显低于治疗前,且观察组较对照组明显降低(P<0.05); 治疗后两组血清MOT水平明显高于治疗前,且观察组较对照组明显升高(P<0.05)。观察组并发症总发生率3.57%较对照组11.90%明显更低(P<0.05)。结论:应用益气开秘方联合伊托必利及乳果糖对气阴两虚型便秘患者的疗效较好,安全性较高,并可改善患者的血清5-HT、MOT及VIP水平。     

降黄散熏蒸联合捏脊、推拿治疗湿热蕴蒸型新生儿病理性黄疸临床研究

目的:观察降黄散熏蒸联合捏脊、推拿治疗湿热蕴蒸型新生儿病理性黄疸的临床疗效。方法:将92例湿热蕴蒸型病理性黄疸患儿按随机数字表法分为观察组和对照组各46例。对照组给予蓝光照射治疗,观察组在对照组基础上加降黄散熏蒸联合捏脊、推拿治疗,2组均治疗5 d。对比2组临床疗效和治疗前后的血清总胆红素水平、免疫球蛋白(Ig)及T细胞亚群的变化,记录黄疸消退时间。结果:观察组临床疗效优于对照组,差异有统计学意义(P<0.05)。治疗后,2组血清总胆红素水平均较治疗前下降(P<0.05),观察组血清总胆红素水平比对照组下降更明显(P<0.05);观察组黄疸消退时间短于对照组(P<0.05)。治疗后,2组血清IgA、IgG、IgM水平均较治疗前升高(P<0.05),观察组IgA、IgG、IgM水平均比对照组升高更明显(P<0.05)。治疗后,2组CD3^+、CD4^+、CD4^+/CD8^+值均较治疗前升高(P<0.05),观察组CD3^+、CD4^+、CD4^+/CD8^+值均比对照组升高更明显(P<0.05)。结论:降黄散熏蒸联合捏脊、推拿治疗湿热蕴蒸型新生儿病理性黄疸,可以有效降低患儿的血清总胆红素水平,缩短退黄时间,提高机体免疫功能。     

评价消风散合黄连解毒汤治疗湿疹效果及价值

目的:探讨评价消风散合黄连解毒汤治疗湿疹效果及价值。方法:选择2017年5—12月治疗湿疹的患者54例作为对象,随机数字表分为对照组(27例)和观察组(27例)。对照组给予常规盐酸西替利嗪片治疗的方法,观察组采用消风散合黄连解毒汤治疗,15 d后对两组治疗方法的患者血清白细胞介素(Interleukin,IL)-4、γ-干扰素(γ-Interferon,IFN-γ)水平和临床治疗效果进行评估,比较两组湿疹患者体内的血清IL-4、IFN-γ含量以及患者治愈、显效、好转、无效以及总有效率的情况。结果:治疗前后两组患者IL-4、IFN-γ差异无统计学意义(P>0.05)。经15 d治疗后,观察组血清IL-4、IFN-γ水平相较于对照组有明显改善,差异有统计学意义(P<0.05),观察组患者总有效率高于对照组,临床治疗效果显著优于对照组(P<0.05)。结论:将消风散合黄连解毒汤治疗用于湿疹,相较于盐酸西替利嗪片治疗,患者血清水平更佳,临床疗效更好,值得推广应用。