氧化锆陶瓷口腔修复材料复合粉体的研制

目的：探讨适合于口腔临床应用的氧化锆陶瓷全瓷美容修复材料复合粉的组成,热处理及复合条件。方法：采用不同粒度、纯度的原料、根据不同的配方,采用沉淀包裹法、共沉地和混合法等制备出了腹 材料用复合粉体,对不同方法制备的复合粉体性进行了综合比较。结果：采用沉淀包裹法可以制备t-ZrO2分布均（0．5μm）、含量高的复合体。结论：采用沉淀包裹法制备的复合体比共沉淀和混合法综合效果好。     

枯矾煅制工艺改进

目的：煅制度优、纯白无杂质的枯矾,适应临床需要,方法：以低压恒温干燥法煅制的枯矾与传统大煅及常压恒温干燥法煅制的枯矾质量进行比较,结果：低压恒温干法煅制的枯矾擀纯无杂质,均匀疏松,洁白如雪,其生产效率,产品质量,失水率均有显著提高,结论：低压恒温干燥法煅制枯矾,压力在41－50kPa之间,同时温度控制在130－180℃之间为适宜。     

In-Ceram与Ceron全瓷底层材料饰瓷后透射率的测定

目的:测定饰瓷后VitaIn-CeramAL2色粉浆涂塑渗透氧化铝、AL2色瓷沉积氧化铝、Z21色粉浆涂塑渗透氧化锆、Z21色瓷沉积氧化锆、Cerconbasecolor氧化锆及Cerconbase氧化锆陶瓷材料的可见光透射率,为临床选择适宜的全瓷系统提供参考。方法:采用分光光度计分别测量6组饰瓷后试样的可见光积分透射率。结果:In-Ceram粉浆涂塑渗透氧化铝的透射率为1.318±0.111,瓷沉积氧化铝2.151±0.044,粉浆涂塑渗透氧化锆0.024±0.002,瓷沉积氧化锆0.047±0.009,Cerconbasecolor氧化锆1.712±0.122,Cerconbase氧化锆2.532±0.125。结论:在6种饰瓷后全瓷底层材料中,按透射率数值由高到低排序为:Cerconbase氧化锆>AL2色瓷沉积氧化铝>Cerconbasecolor氧化锆>AL2色粉浆涂塑渗透氧化铝>Z21色瓷沉积氧化锆和Z21色粉浆涂塑渗透氧化锆。     

Bioceramics in ophthalmology

The benefits of ceramics in biomedical applications have been universally appreciated as they exhibit an extraordinarily broad set of physico-chemical, mechanical and biological properties which can be properly tailored by acting on their composition, porosity and surface texture to increase their versatility and suitability for targeted healthcare applications. Bioceramics have traditionally been used for the repair of hard tissues, such as bone and teeth, mainly due to their suitable strength for load-bearing applications, wear resistance (especially alumina, zirconia and composites thereof) and, in some cases, bone-bonding ability (calcium orthophosphates and bioactive glasses). Bioceramics have been also applied in other medical areas, like ophthalmic surgery; although their use in such a context has been scientifically documented since the late 1700s, the potential and importance of ceramic ocular implants still seem to be underestimated and an exhaustive, critical assessment is currently lacking in the relevant literature. The present review aims to fill this gap by giving a comprehensive picture of the ceramic-based materials and implants that are currently used in ophthalmology and pointing out the strengths and weaknesses of the existing devices. A prospect for future research is also provided, highlighting the potential of new, smart bioceramics able to carry specific added values which could have a significant impact on the treatment of ocular diseases.     

Regular exercise training attenuates pulmonary inflammatory responses to inhaled alumina refinery dust in mice

Exposure to alumina dust has been recently associated with impaired lung mechanics and inflammation. We aimed at evaluating if moderate exercise training prevents these outcomes. Twenty-three female BALB/c mice (25–30 g) were randomly divided in two main groups: control (C) and exercise (E), which were submitted, or not, to 15 min of swimming, 5 days/week during 4 weeks. Then, the animals were exposed for 1 h to either saline solution (CS or ES) or to a suspension of 8 mg/m³ of alumina dust (CA or EA). Twenty-four hours later pulmonary mechanics was determined by the end-inflation occlusion method. Left lungs were prepared for histology and right lungs for TGF-β determination. Static elastance increased after alumina dust exposure independently of swimming. In CA group the viscoelastic component of elastance, the viscoelastic/inhomogeneous pressure, the polymorphonuclear amount, the fraction area of alveolar collapse and TGF-β increased. Thus, exercise training may mitigate the pro-inflammatory response to inhaled aluminum refinery dust.     

纳米氧化铝的体外DNA损伤及氧化应激研究

目的 通过研究不同粒径及不同浓度纳米氧化铝颗粒对中国仓鼠肺细胞(CHL细胞)DNA损伤及氧化应激的影响,探索纳米氧化铝颗粒遗传毒性及作用机制.方法 选用13、50 nm和10μm 3种粒径的氧化铝颗粒为3个粒径组,每种粒径氧化铝又分别设低剂量(15 μg/ml)、中剂量(30 μg/ml)、高剂量(60μg/ml)组,另设空白对照组和阳性对照组.染毒24 h后处理细胞.用荧光显微镜观察cy5.5荧光标记纳米颗粒进入细胞的情况.用单细胞琼脂糖凝胶电泳(SCGE)检测DNA损伤,谷胱甘肽(GSH)、超氧化物歧化酶(SOD)、丙二醛(MDA)评估氧化应激反应的指标.结果 荧光标记的纳米颗粒在细胞核周围分布.SCGE结果显示,与空白对照组相比,各染毒剂量组Olive尾矩有增加趋势,中、高剂量组Olive尾矩均明显增加(P＜0.05).氧化应激指标结果显示,随着染毒剂量的增加各种氧化应激指标明显变化,高剂量组与空白对照组相比,差异有统计学意义(P＜0.05).结论 纳米氧化铝颗粒可以引起CHL细胞DNA损伤和氧化应激反应,氧化应激反应可能是导致遗传毒性的机制之一.     

Crystallographic and morphological analysis of sandblasted highly translucent dental zirconia

Objective

To assess the influence of alumina sandblasting on four highly translucent dental zirconia grades.

不同桩核材料对氧化铝全瓷冠颜色的影响

目的探讨4种不同桩核材料对氧化铝全瓷冠（In-Ceram）颜色的影响。方法选取1颗完整离体牙,进行截冠、完善根管治疗和桩道预备。制备不同材料的桩核预备体和1个氧化铝全瓷冠（In-Ceram）,分为4组（镍铬合金桩核组、金合金桩核组、氧化锆桩核组、纤维桩树脂核组）,每组10颗。采用Minolta CM-700d分光测色仪,测试4组不同桩核材料背景下氧化铝全瓷冠（InCeram）唇面中1/3区域的L^＊、a^＊、b^＊值,分别进行完全随机设计的单因素方差分析和两两比较的LED检验,并根据公式计算和比较色差△E。结果 4种不同的桩核材料背景下氧化铝全瓷冠（In-Ceram）的L^＊、a^＊、b^＊值的差异有统计学意义（FL=334.90,PL=0.000;Fa=4.43,Pa=0.009;Fb=359.22,Pb=0.000）。镍铬合金桩核和金合金桩核组的色差均超过临床可接受水平（△E〉2）;氧化锆桩核和纤维桩树脂核组的色差均不能为肉眼所识别（△E〈1.5）。结论临床应用氧化铝全瓷冠（In-Ceram）进行修复时,尤其在前牙区,不建议使用金属桩核。     

Residual stress profiles in veneering ceramic on Y-TZP,alumina and ZTA frameworks: Measurement by hole-drilling

Objectives

The residual stress profile developed within the veneering ceramic during the manufacturing process is an important predicting factor in chipping failures, which constitute a well-known problem with yttria-tetragonal-zirconia polycrystal (Y-TZP) based restorations. The objectives of this study are to measure and to compare the residual stress profile in the veneering ceramic layered on three different polycrystalline ceramic framework materials: Y-TZP, alumina polycrystal (AL) and zirconia toughened alumina (ZTA).

Methods

The stress profile was measured with the hole-drilling method in bilayered disk samples of 19 mm diameter with a 0.7 mm thick Y-TZP, AL or ZTA framework and a 1.5 mm thick layer of the corresponding veneering ceramic.

Results

The AL samples exhibited increasing compressive stresses with depth, while compressive stresses switching into interior tensile stresses were measured in Y-TZP samples. ZTA samples exhibited compressive stress at the ceramic surface, decreasing with depth up to 0.6 mm from the surface, and then becoming compressive again near the framework.

Significance

Y-TZP samples exhibited a less favorable stress profile than those of AL and ZTA samples. Results support the hypothesis of the occurrence of structural changes within the Y-TZP surface in contact with the veneering ceramic to explain the presence of tensile stresses. Even if the presence of Y-TZP in the alumina matrix seems to negatively affect the residual stress profiles in ZTA samples in comparison with AL samples, the registered profiles remain positive in terms of veneer fracture resistance.     

Combining ageing and wear to assess the durability of zirconia-based ceramic heads for total hip arthroplasty

The degradation of zirconia-based ceramic components for total hip arthroplasty (head and cup) has been the topic of many works. However, the correlation between what is measured in vivo and what is expected from in vitro simulations on hip simulators may be sometimes feeble, especially where zirconia component are concerned, mainly due to a lack of representativeness of in vitro experiments. The present study seeks to explore the combined effects of hydrothermal ageing and wear on zirconia components. It shows that hydrothermal ageing increases the roughness of zirconia components, which in turn might increase the wear rate of the polyethylene counterparts. Moreover, the friction during hip simulation increases the ageing rate of the zirconia components. This auto-accelerating degradation may explain some of the poor long-term in vivo results of zirconia hip prostheses reported in the literature. Finally, it is shown that zirconia-toughened alumina components may be free from this combined degradation.