牙科可切削氧化锆/磷酸镧复相陶瓷的制备及烧结

背景：陶瓷本身质地较脆，抗弯强度较小，在一定程度上限制了其在口腔修复中的应用。氧化锆陶瓷通过其相变增韧，具有较高的抗弯强度和断裂韧性，这一特点可以弥补传统全瓷修复体所存在的脆性问题。 目的：利用纳米氧化锆粉体和磷酸镧复合，初步探索制备新型可切削氧化锆陶瓷。探索牙科可切削氧化锆/磷酸镧复相陶瓷制备烧结特性。 设计：实验通过调整原料的成分、配比、采用不同的工艺路线、不同的烧结方法，确定工艺参数，探索最佳的工艺方式。 单位：上海交通大学医学院附属第九人民医院口腔医学院口腔修复科；上海大学材料科学与工程学院先进无机材料制备工艺实验室。 材料：3Y-TZP（3 mol钇稳定的四方相氧化锆），一次粒径≤50 nm，纯度99.99%，由宜兴新兴锆业有限公司提供。磷酸镧，纯度99.99%，由包头稀土研究院湿法冶金部提供。 方法：实验于2004-01/2006-12在上海交通大学医学院附属第九人民医院口腔修复科完成。预初实验发现磷酸镧含量低于15%强度较高不易加工，而磷酸镧含量高于20%强度明显下降，故将体积百分数分别为15%，18%，20%的磷酸镧加入3Y-TZP（钇稳定四方相氧化锆），采用冷等静压成型（200 MPa），在空气气氛中烧结，采用1 560 ℃，1 580 ℃，1 600 ℃烧结温度，制得不同烧结温度下陶瓷样品。 主要观察指标：用阿基米德法测试各温度下陶瓷体积密度、表观气孔率；用EZ-100万能试验机测试三点弯曲强度。 结果：①瓷体体积密度和表观气孔率：随着烧结温度升高，15%，18%和20%磷酸镧含量的氧化锆/磷酸镧复相陶瓷的体积密度都随之升高，在1 600 ℃时达到最高，分别为5.77，5.42，5.39 g/cm3。表观气孔率则随温度升高而下降，在1 600℃时达到最低，分别为0.88%，1.21%，1.49%。表明瓷块的致密性逐步提高，3种烧结温度烧结的样品体积密度比较，差异无显著性意义（P > 0.05）。②抗弯强度：18%和20%磷酸镧含量的氧化锆/磷酸镧复相陶瓷样品在烧结温度为1 580 ℃前，抗弯强度随烧结温度增加而增加；烧结温度为1 580 ℃时达到最高，分别（772.22±43.43）MPa，（216.03±25.20）MPa和（157.21±9.79）MPa；在1 600℃时抗弯强度反而下降。 结论：采用冷等静压（200 MPa）成型，空气中常压在1 580 ℃烧结，可以得到致密的复合陶瓷。     

烧结温度对氧化锆基台材料机械性能影响的实验研究

目的 研究烧结温度对氧化锆基台材料机械性能的影响。方法 选用纳米氧化锆粉体,通过干压成型和冷等静压技术制备实验试件。试件经1080℃预烧后进行车削加工,然后分别在1350℃和1450℃的温度下进行二次烧结。测试两组试件二次烧结后的弯曲强度、维氏硬度及断裂韧性等机械性能指标,并对数据进行统计分析。结果 1080℃/1450℃烧结组试件的各项机械性能均高于1080℃/1350℃烧结组,二次烧结温度为1450℃时试件的三点弯曲强度、维氏硬度及断裂韧性分别为（858.74?4.94）MPa、（16.00?.42）GPa和（6.96?.55）MPa?m1/2。结论 经1080℃/1450℃烧结的试件具有足够的机械性能,能够满足口腔全瓷基台材料的要求。     

两种嵌体加工技术对树脂嵌体机械性能的影响

背景：复合树脂作为一种既美观又实用的嵌体修复材料,其机械性能的改进成为研发的热点。 目的：用CERAMAGE与TESCERA两种嵌体固化机制作树脂试件,比较两种加工技术对嵌体材料机械性能的影响。 方法：选取两种机器的配套树脂,与两种机器进行交叉配对,分成4组：A、B两组用Tescera树脂分别与TESCERA嵌体机和CERAMAGE嵌体机配对;C、D两组用Ceramage树脂分别与CERAMAGE嵌体机和TESCERA嵌体机配对,分别制作标准试件,测试试件的表面硬度,抗压强度和挠曲强度。 结果与结论：在表面硬度,抗压强度上,A 组高于其他3组;B组高于C、D两组(P <0.05)。在挠曲强度上,C、D两组高于A、B两组(P < 0.05),C、D组间及A、B组间差异无显著性意义。结果表明,用TESCERA嵌体机加工其配套树脂,所得试件的机械性能最佳。     

氧化锆增韧羟基磷灰石纳米复相多孔生物陶瓷的制备与性能*☆

摘要：以过氧化氢为成孔剂将羟基磷灰石、氧化锆、氧化钇粉料按比例混和、成型、烧结制备出氧化锆增韧羟基磷灰石纳米复相多孔生物陶瓷材料,并与纯羟基磷灰石材料的理化性能进行比较。通过阿基米德法测定成型压力为15 MPa所制备的纯羟基磷灰石和多孔生物陶瓷的孔隙率分别为26%和28%。X射线衍射分析表明多孔生物陶瓷材料的物相组成为羟基磷灰石和四方氧化锆相;扫描电镜观察多孔生物陶瓷形貌具有多孔结构;通过万能材料试验机测定在成型压力15 MPa条件下所制备多孔生物陶瓷和纯羟基磷灰石的抗弯强度分别为48.7 MPa和30.8 MPa;弹性模量分别为3 851.27 MPa和 3 071.58 MPa;断裂韧性分别为0.34 MPa•m1/2和0.09 MPa•m1/2。     

着色剂氧化铈及氧化铒对牙科氧化锆陶瓷颜色及性能的影响

背景：有研究提出在氧化锆中添加稀土氧化物,可以在一定程度上改变氧化锆自身颜色,以期满足口腔临床要求,达到美观。 目的：对添加稀土氧化物氧化锆的色度值和机械性能进行评价。 方法：用ShadeEye电脑比色仪测试件的L*a*b*值,用X射线衍射仪(D/max-RB)分析材料的晶相结构,在EZ-100万能实验机上测试其三点弯曲强度。使用扫描电镜观察试样弯曲断口显微形态。 结果与结论：①烧结后所形成的氧化锆试件材料主晶相结构为四方相氧化锆,未见第2种晶相结构。②氧化铈与氧化锆混合呈淡黄色;氧化铒与氧化锆混合呈浅粉红色,并随着剂量的增加,颜色随之加深;二者混合试件使氧化锆呈浅桔黄色,并随着剂量的增加,颜色随之加深。③单独添加二氧化铈后,材料的抗弯强度呈下降趋势,单独添加氧化铒后,材料的抗弯强度呈下降趋势,二氧化铈和氧化铒混合试件抗弯强度随二氧化铈和氧化铒含量的增加而降低,单独添加二氧化铈仅少量降低了抗弯强度,当加入氧化铒后对材料强度降低的影响更加明显。表明,稀土氧化物与氧化锆混合可以改变氧化锆自身颜色,并且具有一定的抗弯性。     

羟基磷灰石/单壁碳纳米管复合材料的表征

背景：羟基磷灰石具有接近自然人骨的强韧度和优越的生物相容性,但其力学性能却较差。 目的：制成并研究一种新型生物活性材料(羟基磷灰石/单壁碳纳米管复合材料)的各种性质。 方法：利用原位合成法制备羟基磷灰石单壁碳纳米管复合材料,并对其红外光谱、微观结构及XDR衍射分析,力学性能进行测试,对不同SWNT含量的SWNT/HAp复合材料弯曲强度与断裂韧性比较分析。 结果与结论：成功制备出的纳米羟基磷灰石单壁碳纳米管复合材料,其抗弯强度最大增幅将近50%,达到73 MPa;而断裂韧性的最大提高幅度为3倍,达到2.6 MPa•m1/2。随着单壁碳纳米管复合材料含量的增加,复合材料的弯曲强度与断裂韧性呈现出缓慢上升的趋势。提示,纳米羟基磷灰石单壁碳纳米管复合材料显著提高了接近自然人骨的纳米级磷灰石骨材料的抗弯强度和断裂韧性,从而克服传统支撑骨材料的力学性能缺陷。     

树脂黏结剂及氧化锆陶瓷剪切黏结强度与不同表面处理方式的关系

摘要 背景：目前对适合应用于氧化锆陶瓷的表面处理方式仍有争论。有学者认为传统硅烷化处理无法提高氧化锆陶瓷的黏结强度，但也有文献报道经硅烷化处理或喷砂处理之后进行硅烷化处理均可提高氧化锆陶瓷的黏结强度。 目的：测试不同表面处理后氧化锆陶瓷与树脂黏结剂之间的黏结强度，探讨适合口腔氧化锆陶瓷黏结的表面处理方法。 方法：将氧化锆陶瓷胚体切割成15 mm×10 mm×3 mm的试件50个，烧结后根据对其表面的处理方式不同分为以下5组：对照组(不处理)、硅烷偶联剂组、喷砂组、喷砂+硅烷偶联剂组、喷砂+硅溶胶+硅烷偶联剂组。将所有试件与树脂黏结剂黏结，形成剪切测试样本，于疲劳试验机上测试其剪切黏结强度，观察所有测试后样本的破坏模式。 结果与结论：4个实验组的剪切黏结强度值均明显高于对照组(P < 0.05)，喷砂+硅烷偶联剂组剪切强度值最高。除喷砂组与喷砂+硅溶胶+硅烷偶联剂组、喷砂+硅烷偶联剂组与喷砂+硅溶胶+硅烷偶联剂组间比较差异无显著性意义(P > 0.05)外，其余每两组间比较差异均有显著性意义(P < 0.05)。说明喷砂和硅烷偶联剂均能够提高氧化锆陶瓷与树脂黏结剂的黏结强度；喷砂联合硅烷偶联剂是最适合牙科氧化锆陶瓷黏结的表面处理方法。硅溶胶未明显影响氧化锆陶瓷与树脂黏结剂的黏结强度。 关键词：氧化锆陶瓷；树脂黏结剂；表面处理；剪切黏结强度；口腔生物材料 doi:10.3969/j.issn.1673-8225.2010.42.019     

4002/牙科纳米材料3Y-TZP的性能及微观结构(英文他译）

摘要 背景：在临床应用中,全瓷修复可解决以往材料的美观与安全等方面的问题而被越来越广泛的接受,尤其是高强度高韧性的氧化锆全瓷材料倍受关注。 目的：分析摩尔分数为3%氧化钇稳定的四方多晶氧化锆(3Y-TZP)的烧结性能、力学性能及微观结构。 设计、时间及地点：材料学表征,观察实验,于2007-02/2009-05在解放军第四军医大学口腔医学院修复实验室设计实施完成。 材料：纳米3Y-TZP粉体(粒度约50 nm) 由上海双鼎纳米材料有限公司提供。 方法：纳米3Y-TZP粉末与浓度7%聚乙烯醇混合,搅拌均匀后造粒,双向干压成型,制备圆盘及长条状试件,常压烧结。其中圆形试样用于烧结性能测试,长条形试样用于力学性能及微观结构测试。 主要观察指标：Archimedes法测试烧结性能,并检测三点抗弯强度、断裂韧性;扫描电镜观察断面形貌;X射线衍射分析晶相组成,比较表面与断面的四方相含量。 结果：纳米3Y-TZP在1 500 ℃烧成,结构致密,三点抗弯强度(921.7±44.2) MPa;断裂韧性(10.2±1.6) MPa•m1/2。微观形貌示烧结后结构均匀致密,缺陷少,晶粒细小,粒径约0.3 µm。X射线衍射分析材料表面为四方相,无单斜相衍射峰;断面四方相81%,单斜相19%。 结论：纳米3Y-TZP材料低温烧结,颜色美观,微观结构致密均匀,强韧性好,适宜做牙科全瓷材料。 关键词：3Y-TZP;烧结性能;力学性能;显微结构;纳米粉体     

氧化锆陶瓷和钛合金表面粗糙度与细菌黏附的比较

实验于2006-03/06在山西医科大学微生物实验室完成。分别制作氧化锆陶瓷试件和Titan合金试件各6个。实验分为2组，氧化锆陶瓷抛光组：Cercaon氧化锆薄片磨光后，用EVE专用抛光轮高度抛光。钛合金抛光组：将钛合金原始铸件依次用粗砂纸、水砂纸(依次为200，600，800，1 000，1 200，1 500，2 000 目)逐级磨光，再用抛光轮抛光。采用精密粗糙度测试仪检测各样本的表面粗糙度；然后将各样本置于变形链球菌的培养液中，在37 ℃条件下，静止培养状态下培养1 h后，荧光显微镜下计数黏附细菌的数量，并通过扫描电子显微镜观察各样本的表面形貌。结果显示，两组间表面粗糙度无显著差异(P > 0.05)，但钛合金抛光组试件黏附细菌数多于氧化锆陶瓷抛光组试件黏附细菌数(P < 0.01)。扫描电镜显示，氧化锆陶瓷抛光组试件表面散在少量细小孔隙，而钛合金抛光组试件表面未见细小孔隙，但有较多裂隙和凹陷。     

氧化锆陶瓷材料的生物相容性

摘要 背景：已有大量研究表明,氧化锆陶瓷具有优良的生物学性能,但作为牙种植基台的研究在国内还鲜见报道,将其应用于种植牙基台上的生物学性能还需要进一步的验证。 目的：评价牙种植基台制作材料氧化锆陶瓷的生物相容性。 方法：将氧化锆陶瓷圆形试件固定在Wistar大鼠左颊黏膜表面,右侧用牙胶试件作为对照,使两组试件与颊黏膜紧密贴合但无压迫,术后2周应用大体观察和组织学方法观察口腔黏膜与氧化锆陶瓷材料的生物学反应;将氧化锆陶瓷棒形试件植入Wistar大鼠背部皮下组织内,于植入后1,2,4,8周应用大体观察和组织学方法动态观察皮肤组织与氧化锆陶瓷材料的生物学反应。 结果与结论：氧化锆陶瓷圆形试件固定后,大鼠颊黏膜局部组织未见异常,与对照组比较差异无显著性意义;氧化锆陶瓷棒形试件植入第1周可见局部组织轻微红肿,组织切片可见少量炎性细胞,2~8周红肿消退,组织切片见纤维包膜形成并逐渐变薄,到8周时包膜形成致密纤维,未见炎性细胞。提示氧化锆陶瓷材料与口腔黏膜、皮肤及皮下组织具有良好的生物相容性。 关键词：氧化锆陶瓷;口腔黏膜;皮肤组织;皮下组织;生物相容性;口腔生物材料 doi:10.3969/j.issn.1673-8225.2011.12.016     

Epilepsy and anomalies of neuronal migration: MRI and clinical aspects

Neuronal migration disorders are the result of disturbed brain development. In such disorders, neurons are abnormally located. In diagnosing these conditions, magnetic resonance imaging is superior to any other imaging technique. This enables us to improve our knowledge of the clinical correlates of neuronal migration. With reference to migrational disorder, a retrospective study of all 303 patients with epileptic seizures referred for magnetic resonance imaging during a 3-year period was performed, 13 patients (aged 12-41, mean age 27) were identified. They represent 4.3% of the entire study group. Of the patients with known epilepsy, 6.7% and of the mentally retarded, 13.7% had migrational disorders. Four patients had schizencephaly as the dominant finding, one was classified as hemimegalencephaly, 2 had isolated heterotopias, and 6 had localized pachy- and/or poly-microgyria. The clinical pictures are complex. Ectopias of grey matter are recognised foci of epilepsy, but from an epileptological and a clinical viewpoint little attention has been given to these disorders. The present study shows that malmigration is not rare in epilepsy patients, especially not in the mentally retarded.     

Hepatic Considerations in the Use of Antiepileptic Drugs

Summary: Virtually all of the major antiepileptic drugs (AEDs) can cause hepatotoxicity, although fatal hepatic reactions are rare. The mechanisms, incidences, and risk profiles for such reactions differ from drug to drug. With carbamazepine and phenytoin, hepatotoxicity may be due to drug hypersensitivity. Although the profiles of patients at risk have not been well-defined for these two antiepileptic drugs, it would appear from reports in the literature that older adolescents and adults are at higher risk than children of developing serious or fatal hepatotoxicity. Once hepatotoxicity develops, mortality rates are 10–38% with phenytoin and 25% for carbamazepine. The risk profile for valproate fatal hepatotoxicity has been more clearly defined. Those at primary risk of fatal hepatic dysfunction are children under the age of 2 years who are receiving multiple anticonvulsants and also have significant medical problems in addition to severe epilepsy. The risk is considerably lower for patients over the age of 2 years on valproate monotherapy. In contrast to the risk profile with other AEDs, adults receiving valproate as monotherapy have the lowest risk of hepatotoxicity. Fatal hepatic dysfunction coincident with valproate may be the result of aberrant drug metabolism. Concomitant use of AEDs that induce microsomal P450 enzymes (e.g., phenytoin and phenobarbital) may enhance the production of a toxic metabolite, and hence the greater risk of hepatotoxicity with polypharmacy.     

Vascular Malformations and Epilepsy: Clinical Considerations and Basic Mechanisms

Summary: Vascular malformations (VMs) are associated with epilepsy. The natural history of the various VMs, clinical presentation, and tendency to provoke epilepsy determine treatment strategies. Investigations have probed the mechanisms of epileptogenesis associated with these lesions. Electrophysiologic changes are associated with epileptogenic cortex adjacent to VMs. Putative pathophysiologic mechanisms of epileptogenesis include neuronal cell loss, glial proliferation and abnormal glial physiology, altered neurotransmitter levels, free radical formation, and aberrant second messenger physiology.     

Classification of methods in transcranial Electrical Stimulation (tES) and evolving strategy from historical approaches to contemporary innovations

Transcranial Electrical Stimulation (tES) encompasses all methods of non-invasive current application to the brain used in research and clinical practice. We present the first comprehensive and technical review, explaining the evolution of tES in both terminology and dosage over the past 100 years of research to present day. Current transcranial Pulsed Current Stimulation (tPCS) approaches such as Cranial Electrotherapy Stimulation (CES) descended from Electrosleep (ES) through Cranial Electro-stimulation Therapy (CET), Transcerebral Electrotherapy (TCET), and NeuroElectric Therapy (NET) while others like Transcutaneous Cranial Electrical Stimulation (TCES) descended from Electroanesthesia (EA) through Limoge, and Interferential Stimulation. Prior to a contemporary resurgence in interest, variations of transcranial Direct Current Stimulation were explored intermittently, including Polarizing current, Galvanic Vestibular Stimulation (GVS), and Transcranial Micropolarization. The development of these approaches alongside Electroconvulsive Therapy (ECT) and pharmacological developments are considered. Both the roots and unique features of contemporary approaches such as transcranial Alternating Current Stimulation (tACS) and transcranial Random Noise Stimulation (tRNS) are discussed. Trends and incremental developments in electrode montage and waveform spanning decades are presented leading to the present day. Commercial devices, seminal conferences, and regulatory decisions are noted. We conclude with six rules on how increasing medical and technological sophistication may now be leveraged for broader success and adoption of tES.     

Carbamazepine Efficacy and Utilization in Children

Summary: Carbamazepine is effective for preventing partial and generalized tonic-clonic seizures in children. Although absence epilepsies are more common in children than adults, an estimated 80% of children with epilepsy have seizure types or epilepsies that are potentially responsive to carbamazepine. The differential diagnosis of ictal staring is an especially important issue in children because absence and atypical absence seizures are more prevalent in children than adults. Age-related pharmacokinetic differences and drug interactions are major considerations in children. On average, children have higher clearance rates of carbamazepine, shorter half-lives, and higher ratios of carbamazepine-10, 11-epoxide to carbamazepine than adults. In addition, children with severe epilepsy are more likely to require multiple-drug therapy, which can lead to complex drug interactions. When carbamazepine is administered along with valproate, drug protein binding interactions can cause intermittent side effects.     

Neonatal Seizures: Problems in Diagnosis and Classification

Summary: The clinical identification of neonatal seizures is critical for the recognition of brain dysfunction; however, diagnosis is often difficult because of the poorly organized and varied nature of these behaviors. Current classification systems are limited in their ability to communicate motor, autonomic, and electroencephalo-graphic features of seizures precisely and to provide a basis for uniform effective diagnosis, therapy, and determination of prognosis. Recent investigations of neonates, utilizing bedside electroencephalographic/polygraphic/ video monitoring techniques, have provided the basis for improved diagnosis and classification of seizures in the newborn. These studies have demonstrated that not all clinical phenomena currently considered to be seizures require electrocortical epileptiform activity for their initiation or elaboration. In addition, the specific clinical character of the phenomena considered to be seizures, the clinical state of the infant, and the character of the EEG indicate the probable pathophysiological mechanisms involved and suggest probable etiologies, prognosis, and therapy. Similarities between animal models that demonstrate reflex physiology and neonates with motor automatisms and tonic posturing suggest that these clinical behaviors may not be epileptic in origin but, rather, primitive movements of progression and posture mediated by brainstem mechanisms. Although not all clinical behaviors currently considered to be neonatal seizures may have similar pathophysiological mechanisms, they are clinically significant because they all indicate brain dysfunction.     

Valproate Monotherapy in the Management of Generalized and Partial Seizures

Summary: For decades, therapeutic tradition has promoted the concept of polypharmacy in the management of epilepsy. In recent years, however, studies have shown that, for most patients, monotherapy can provide comparable or better seizure control than administration of multiple anticonvulsants, while diminishing the potential for adverse reactions, drug interactions, and poor compliance. Valproate is an important monotherapeutic agent that is highly effective in the control of idiopathic primary and secondarily generalized epilepsies, and partial seizures that do not generalize. Comparative studies have found that valproate is at least as effective as phenytoin and carbamazepine in the treatment of generalized and partial seizures. Given the similar efficacy, other factors such as pharmacokinetics and side effects may therefore determine anticonvulsant selection for monotherapy.     

Un nouveau cadre conceptuel de travail pour la psychiatrie

In an attempt to place psychiatric thinking and the training of future psychiatrists more centrally into the context of modern biology, the author outlines the beginnings of a new intellectual framework for psychiatry that derives from current biological thinking about the relationship of mind to brain. The purpose of this framework is twofold. First, it is designed to emphasize that the professional requirements for future psychiatrists will demand a greater knowledge of the structure and functioning of the brain than is currently available in most training programs. Second, it is designed to illustrate that the unique domain which psychiatry occupies within academic medicine, the analysis of the interaction between social and biological determinants of behavior, can best be studied by also having a full understanding of the biological components of behavior.     

Special Pharmacokinetic Considerations in Children

Summary: Pediatric patients have greater degrees of pharmacokinetic variability and unpredictability than adults. This variability results from the effects of pharmacogenetics, age and growth, prior and current comedication, and disease. Newborns with seizures have the least predictable dosage requirements, and their needs change as drug-eliminating mechanisms mature in the neonatal period. Infants have the highest relative capacities to eliminate antiepileptics of any age group and require the largest relative doses. In addition to age-related trends, children demonstrate the same drug-specific, pharmacokinetic phenomena that adults do, including nonlinear phenytoin elimination, nonlinear valproate binding, and autoinduction of carbamazepine. Intercurrent illness and drug interactions further modify the age-related pharmacokinetic patterns in children and make dosage requirements even more unpredictable. Recent studies have shown that febrile illness can affect drug elimination, sometimes decreasing drug levels by 50% or more. Intermittent treatment with benzodiazepines administered either orally or rectally can be an important adjunct and help minimize this type of problem for children with marginally controlled epilepsy. Intermittent benzodiazepines are also helpful for children who have febrile seizures and who need only occasional antiepileptic protection.