根管治疗术远期疗效的影响因素

根管治疗术（root canal therapy,RCT）是治疗牙髓病、根尖周病的主要方法.影响根管治疗术远期疗效的因素较多,而RCT前根尖周状态和根充位置是两大主要因素.     

两种后牙根管预备方法的临床效果比较

目的 :评估 2种后牙根管预备方法的临床效果。方法 :采用机用镍钛扩大锉 (ProFile)和手用不锈钢扩大锉 (K file)扩大后牙根管 ,并对 2组病例术后疼痛以及充填情况加以比较。结果 :发现机用镍钛扩大锉扩大后牙根管 ,具有去除根管感染物质彻底 ,根管形态保持良好 ,速度快 ,术后疼痛率较低的优点 ,但易出现断针。而手用不锈钢扩大锉扩大后牙根管速度较慢 ,术后疼痛率略高 ,但不易出现断针 ,操作上容易掌握。结论 :2种后牙根管方法都有优缺点 ,可结合起来使用。     

试尖对根管充填质量影响的研究

目的：了解试尖对侧向加压法根管充填质量的影响因素。方法：随机提取我院1998年10月至2004年12月所完成的根管充填病例的X线片1000例，按试尖与未试尖，分别对前牙、前磨牙和磨牙根管充填质量进行分析。结果：在482例未试尖根管充填病例中，前牙、前磨牙和磨牙的适充比例分别为46％、37％和23％，欠充为20％、29％和47％。超充为34％、33％和29％：在518例试尖病例中，前牙、前磨牙和磨牙的适充比例分别为68％、62％和51％，欠充为6％、12％和13％，超充为25％、24％和36％。结论：在侧向加压法根管充填中，试尖可明显改善充填质量。     

The effect of apical foramen patency on condensation stresses

Abstract Mathematical models and computer-based engineering tools were used to evaluate the effect of a patent or closed apical foramen on stresses that are produced within gutta-percha during condensation. We examined a mathematical model of a tapered canal with a definite constriction and compared the results when the apical foramen was closed or open. When the canal was closed an almost constant stress was seen throughout the gutta-percha. When the foramen was open a sharp increase in lateral stress was observed in the apical portions of the canal. The constriction near the foramen caused the gutta-percha to be squeezed together and the stress was increased. This increases the likelihood that the gutta-percha is well adapted to the apical constriction. However, the stresses are also transferred to the surrounding dentin, resulting in a stress concentration near the apical foramen where the bulk of dentin is minimal.     

抗生素糊剂充填乳牙根管疗效观察

目的 探索一种疗程短、疗效好、患儿及家长易接受的根管治疗方法.方法 选择需行根管治疗的患儿162例,常规根管清理,试验组用抗生素糊剂充填乳牙根管,对照组用氢氧化钙糊剂,比较两组疗效.结果 经1年随访观察,抗生素组和氢氧化钙组乳牙根管充填成功率差异无显著意义.结论 用抗生素糊剂一次充填乳牙根管疗程短、疗效好,值得临床推广使用.     

Droplet‐in‐Droplet Polymer Blend Microstructures: a Potential Route Toward the Recycling of Co‐mingled Plastics

The problem of recycling co‐mingled plastics is primarily related to the problem of multiple interfaces in multicomponent immiscible polymer blends. Here, we study a new concept where thermodynamically driven polymer segregation and phase encapsulation are used to locate multiple phases within one of two major phases. Starting from a co‐continuous blend of HDPE and PP, hierarchically encapsulated PS/PMMA/PC composite droplets are found to be exclusively located within PP when the principal HDPE/PP interface is compatibilized. The mechanical properties of the structures demonstrate an improved tensile strength and modulus as well as ductility under the appropriate processing conditions. This approach has potential as a novel route toward the recycling of co‐mingled plastics.     

热塑牙胶充填根管临床观察

目的：观察连续波热塑牙胶注射法充填根管的临床效果.方法：选择360例根管治疗患者,共380颗牙,其中240颗牙用热塑牙胶注射充填仪做连续波热塑牙胶充填根管,140颗牙用常规冷牙胶侧方加压充填根管,通过X线片比较两组病例的充填质量并比较两组病例间每根管根充需用时间.结果：X线片显示连续波热塑牙胶充填组欠填率1.67％,超填率2.91％,恰填率95.41％,冷牙胶侧压充填组欠填率8.57％,超填率2.85％,恰填率88.57％,比较两组间欠填率与恰填率有统计学差异（P＜0.05）,连续波热塑牙胶充填组平均每根管根充时间8 min.冷牙胶侧压组充填平均每根管根充时间12 min.连续波热塑牙胶充填组缩短根充时间30％.结论：连续波热塑牙胶充填术比冷牙胶侧方加压充填术根管充填质量更高且节约根充时间,提高了工作效率.     

A Quantitative Comparison of Physical Accuracy and Numerical Stability of Lattice Boltzmann Color Gradient and Pseudopotential Multicomponent Models for Microfluidic Applications

The performances of the Color-Gradient (CG) and the Shan-Chen (SC) multicomponent Lattice Boltzmann models are quantitatively compared side-by-side on multiple physical flow problems where breakup, coalescence and contraction of fluid ligaments are important. The flow problems are relevant to microfluidic applications, jetting of microdroplets as seen in inkjet printing, as well as emulsion dynamics. A significantly wider range of parameters is shown to be accessible for CG in terms of density-ratio, viscosity-ratio and surface tension values. Numerical stability for a high density ratio $\mathcal{O}(1000)$ is required for simulating the drop formation process during inkjet printing which we show here to be achievable using the CG model but not using the SC model. Our results show that the CG model is a suitable choice for challenging simulations of droplet formation, due to a combination of both numerical stability and physical accuracy. We also present a novel approach to incorporate repulsion forces between interfaces for CG, with possible applications to the study of stabilized emulsions. Specifically, we show that the CG model can produce similar results to a known multirange potentials extension of the SC model for modelling a disjoining pressure, opening up its use for the study of dense stabilized emulsions.     

A Two-Dimensional Second Order Conservative Front-Tracking Method with an Original Marker Advection Approach Based on Jump Relations

A two-dimensional front-tracking method is developed for handling complex shape interfaces satisfying the volume conservation. In order to validate the proposed front-tracking method, a complete convergence study is carried out on several analytical test cases for which the interface is widely stretched and deformed. Comparisons to different existing approaches show that our front-tracking method is second order accurate in space with lower errors than existing interface tracking techniques of the literature.We also propose an original marker advection method which takes into account the jump relations valid at interface in order to deal with the contrast of physical properties encountered in two-phase flow simulations. The conservative front-tracking method computed in this work is shown to be able to describe interfaces with high accuracy even for poorly resolved Eulerian grids.