Monolithic crowns fracture analysis: The effect of material properties,cusp angle and crown thickness

ObjectivesThis study aimed to investigate the collective influence of material properties and design parameters on the fracture behavior of monolithic dental crowns.MethodsThree-dimensional (3D) models (N = 90) with different combinations of design parameters (thickness, cusp angle and occlusal notch geometry) and material type (lithium disilicate, feldspar ceramic, zirconia, hybrid resin ceramic and hybrid polymer-infiltrated ceramic) were developed for the failure analysis using extended finite element method (XFEM) to identify the stress distribution, crack initiation load, fracture surface area and fracture pattern. Analytical formulation, in vitro fracture tests and fractographic analysis of dedicated models were also performed to validate the findings of the XFEM simulation.ResultsFor all material types considered, crowns with a sharp occlusal notch design had a significantly lower fracture resistance against occlusal loading. In most of the models, greater crown thickness and cusp angle resulted in a higher crack initiation load. However, the effect of cusp angle was dominant when the angle was in the low range of 50° for which increasing thickness did not enhance the crack initiation load.SignificanceComparing the critical load of crack initiation for different models with the maximum biting force revealed that for the studied monolithic materials excluding zirconia, a design with a rounded occlusal notch, 70° cusp angle and medium thickness (1.5 mm occlusal) is an optimum combination of design parameters in terms of tooth conservation and fracture resistance. Zirconia crowns exhibited sufficient strength for a more conservative design with less thickness (1.05 mm occlusal) and sharper cusp angle (60°).     

移动协同办公在病区物资管理中的应用

目的利用智能手机软件辅助实现病区物资的移动智能化管理。方法将病区物资分类整理并制作成Excel工作表,通过智能手机和微信、WPS office手机软件功能进行工作表编辑、查询定时提醒、共享、权限设置,以实现病区物资移动智能化管理。结果通过该应用,病区建立了高效低耗的物资管理制度,物资管理缺陷率明显下降,实施前后差异有统计学意义(P<0.05)。结论基于移动协同办公进行病区物资管理是可行的,获得院内临床护士一致认可,具有临床推广价值。     

基于物料性质表征技术的蒲地蓝消炎口服液 儿童用药顺应性改善研究

蒲地蓝消炎口服液安全有效,显效迅速,临床应用广泛,但在儿科用药领域,由于用药剂量不明确与口服顺应性差成为制约其发展的主要原因。基于此,本研究通过分析其问题产生的根源并深入探究其解决方案,通过物料性质表征技术、复合矫味技术、剂型优化技术以提升蒲地蓝消炎口服液的口服顺应性,同时探讨蒲地蓝消炎口服液的儿童精准用药策略,为儿童精准用药的临床前研究提供技术指导。     

Risk of child poverty and social exclusion in two Spanish regions: social and family determinants

ObjectiveDescribe the risk of poverty and social exclusion in children aged 8-11 years from Gipuzkoa and Valencia (Spain), through AROPE (At Risk Of Poverty or Social Exclusion) indicators, and evaluate their associated factors in the INMA Project (Childhood and Environment).MethodFamilies in Gipuzkoa and Valencia (394 and 382, respectively) completed a questionnaire in 2015-2016. Low work intensity (LWI), at risk of poverty (RP) and material deprivation (MD) were estimated. AROPE consisted in meeting any of the previous sub-indicators. Socio-demographic, family and parental characteristics were considered. Frequencies, Venn's diagrams, and chi-square and Fisher tests were used in bivariate analysis and logistic regression in multivariate analysis.ResultsFor LWI, RP, MD and AROPE, prevalence of 2.5%, 5.6%, 2.3% and 7.2% were obtained in Gipuzkoa, and 8.1%, 31.5%, 7.8% and 34.7% in Valencia, respectively. In the multivariate analysis, the AROPE was associated in both areas with maternal social class and non-nuclear families. In Gipuzkoa, it was also related to maternal education. In Valencia, other factors were the mother's foreign origin, and paternal education and smoking.ConclusionThere is higher AROPE prevalence in Valencia. Social class and family type were shared factors, but a differential pattern is observed in other social determinants. It is essential to implement social policies to reduce this axis of inequalities in health, especially in childhood.     

Single-source dual energy CT to assess myocardial extracellular volume fraction in aortic stenosis before transcatheter aortic valve implantation (TAVI)

PurposeTo assess myocardial extracellular volume fraction (ECV) measurement provided by a single-source dual-energy computed tomography (SSDE-CT) acquisition added at the end of a routine CT examination before transcatether aortic valve implantation (TAVI) compared to cardiac magnetic resonance imaging (MRI).Materials and methodsTwenty-one patients (10 men, 11 women; mean age, 86 ± 4.9 years [SD]; age range: 71–92 years) with severe aortic stenosis underwent standard pre-TAVI CT with additional cardiac SSDE-CT acquisition 7 minutes after intravenous administration of iodinated contrast material and myocardial MRI including pre- and post-contrast T1-maps. Myocardial ECV and standard deviation (σECV) were calculated in the 16-segments model. ECV provided by SSDE-CT was compared to ECV provided by MRI, which served as the reference. Analyses were performed on a per-segment basis and on a per-patient involving the mean value of the 16-segments.ResultsECV was slightly overestimated by SSDE-CT (29.9 ± 4.6 [SD] %; range: 20.9%–48.3%) compared to MRI (29.1 ± 3.9 [SD] %; range: 22.0%–50.7%) (P < 0.0001) with a bias and limits of agreement of +2.3% (95%CI: −16.1%– + 20.6%) and +2.5% (95%CI: −2.1%– + 7.1%) for per-segment and per-patient-analyses, respectively. Good (r = 0.81 for per-segment-analysis) to excellent (r = 0.97 for per-patient-analysis) linear relationships (both P < 0.0001) were obtained. The σECV was significantly higher at SSDE-CT (P < 0.0001). Additional radiation dose from CT was 1.89 ± 0.38 (SD) mSv (range: 1.48–2.47 mSv).ConclusionA single additional SSDE-CT acquisition added at the end of a standard pre-TAVI CT protocol can provide ECV measurement with good to excellent linear relationship with MRI.     

适应性回归分析(Ⅲ)——构建具有混合结构的回归模型

本文目的是通过两个实例介绍适应性回归样条算法对具有混杂结构的数据集进行回归建模的实践。当一个数据集包含多个不同的回归模型时,只要给定分类变量的具体取值,SAS中的"ADAPTIVEREG过程"可以比较准确地发掘出其内在规律,并以图形方式呈现模型对资料的拟合效果,还能呈现由"基函数"及其组合所构造出的"回归模型"。图形呈现的结果确实可以给分析者提供一些有价值的"分析线索"或"积极暗示",缩小"探索性研究的空间"。     

A review of the effects of the cell environment physicochemical nanoarchitecture on stem cell commitment

Physicochemical features of a cell nanoenvironment exert important influence on stem cell behavior and include the influence of matrix elasticity and topography on differentiation processes. The presence of growth factors such as TGF-β and BMPs on these matrices provides chemical cues and thus plays vital role in directing eventual stem cell fate. Engineering of functional biomimetic scaffolds that present programmed spatio-temporal physical and chemical signals to stem cells holds great promise in stem cell therapy. Progress in this field requires tacit understanding of the mechanistic aspects of cell-environment nanointeractions, so that they can be manipulated and exploited for the design of sophisticated next generation biomaterials. In this review, we report and discuss the evolution of these processes and pathways in the context of matrix adhesion as they might relate to stemness and stem cell differentiation. Super-resolution microscopy and single-molecule methods for in vitro nano-manipulation are helping to identify and characterize the molecules and mechanics of structural transitions within stem cells and matrices. All these advances facilitate research toward understanding of stem cell niche and consequently to developing new class of biomaterials helping the “used biomaterials” for applications in tissue engineering and regenerative medicine.     

Characterization of Leachates from 6 Root Canal Sealers

Introduction

The aim of this study was to evaluate 6 different endodontic sealers by characterizing their leachates and comparing their solubility in water over a 4-week period.

下颌骨缺损不同植入材料重建的X线影像学追踪观察

目的探讨下颌骨缺损重建的各种治疗方法的效果。方法对经病理确诊且经过治疗的67例下颌骨缺损重建患者的X线片表现进行回顾性分析,比较各种治疗方法的治疗效果。结果在下颌骨切除术后的67例患者,进行了即刻或二期植骨修复治疗。肋骨植入28例,其中7例感染,3例复发,1例植入骨断裂错位愈合;髂骨植入16例,其中1例感染;腓骨植入12例,其中3例同期行种植体的植入,共5枚;人工骨植入6例,其中1例为有机玻璃植入后感染再行人工骨植入,l例术后复发;有机玻璃植入2例,术后均感染;人工高分子材料网及骨松质植入1例;单纯钛板植入2例;复合植入物1例。结论肋骨、髂骨、腓骨植骨修复治疗为目前下颌缺损重建的主要方式,而带血管蒂的游离腓骨组织瓣移植术具有肋骨、髂骨移植术不可比拟的优点,是下颌骨切除术后修复重建的最佳方法之一。