基于弓丝预应力分析的正畸有限元仿真

利用CT扫描的牙齿数据,使用逆向工程软件Mimics和CAD软件Catia,建立了具有较高精度的包含正畸托槽、牙弓、牙周膜和颌骨在内的可以进行布尔运算的实体模型;基于高等机构学的理论,将弓丝装配过程等效为托槽移动的过程,分析求得该等效过程中托槽运动的参数,利用所得参数对等效过程进行有限元仿真,以获得弓丝初始预应力及弓丝作用在每颗牙齿上的初始力和力矩;将牙齿和牙槽骨建模为刚性接触体,牙周膜为弹性体,施加分析获得的初始力系,进行接触分析,得到正畸临床状态下整个上牙颌牙周膜的应力大小和分布.通过对矫治器和牙弓、槽骨联合建模,并使用空间螺旋坐标系,本方法可以获得临床状态下的正畸矫治力和牙周组织响应,为正畸理论研究和临床实践提供指导.     

三棱滑切固定矫治器--结构设计与应用原理

目的开发设计一种新型的固定矫治器：三棱滑切固定矫治器，用于牙颌畸形的正畸治疗，对其结构设计和应用原理进行探讨分析。方法三棱滑切固定矫治器的结构，以三棱形弓丝和具有三角槽沟的托槽为主体，由它控制矫治牙在各个方向的移动而发挥矫治作用。结果对该矫治器的结构做出定性设计，分析探讨其调控牙齿正畸移动的方式主要为通过三棱弓丝的一个刃状边棱与托槽三角沟槽的一个边面相切，借助于弓丝本身的弹性形变力和弓丝的外加引导力而对矫治牙齿施以滑动和切入机制的矫治力。结论三棱形弓丝和与之匹配的三角槽沟托槽是这类矫治器的主要结构特征；角——槽切合锁入式结构设计在确保弓丝与槽沟完全吻合的条件下实现了弓丝入槽——出槽顺畅自由，易于临床使用和精确调控牙位的目的；“棱面相切——加力引导切入——渐进式加力”到牙齿，更加符合持续、轻力的现代口腔正畸施力原则．     

转矩作用对微植体矫治力系内收上前牙影响的三维有限元研究

目的研究转矩力的作用对于微植体矫治力系内收上前牙的影响。方法利用MIMICS软件和有限元软件ABAQUS,建立微植体矫治力系的有限元模型,并在该模型上计算分析有无转矩及转矩作用区域对中切牙和侧切牙移动趋势的影响。结果不加转矩时,中切牙和侧切牙都表现出舌向倾斜的趋势。在100g·cm转矩力的作用下,随着转矩作用区域的增大,中切牙的唇向移动趋势逐渐减小,侧切牙由舌向移动逐渐转为唇向移动。结论转矩能够有效改变牙齿的移动方式,如果转矩从中切牙之间开始向两侧远中方向逐渐减少,效果会更好。     

实验性牙移动模型大鼠构建:牙齿移动后空口咀嚼时间变化规律

背景:错颌畸形正畸交互牵引移动牙齿产生有规律自发性疼痛,但是疼痛的中枢神经传导通路以及疼痛的基本机制并不清楚。目的:建立实验性牙移动模型大鼠,观察大鼠牙移动后单位时间空口咀嚼行为学变化规律。方法:将大鼠随机分为空白组,阴性对照组和模型组,模型组使用改良Colin.K.法,用镍钛丝正畸矫治力交互牵引大鼠上颌前后牙建立大鼠牙移动模型;空白组无交互牵引装置;阴性对照组不加矫治力;分别检测在牙移动后4,12 h,移动后1,3,5,7 d大鼠空口咀嚼行为学改变;牙移动后1 d,牙齿移动分别加力30,60,90 g,观察大鼠空口咀嚼相关行为学变化。结果与结论:与阴性对照组和空白组比较,模型组大鼠牙移动后4 h开始,空口咀嚼时间总和开始增加,牙移动后12 h空口咀嚼时间明显增加(P0.05),牙移动后1 d达到峰值(P0.01),随后缓慢下降至7 d。牙齿移动后1 d,模型组大鼠施加正畸矫治力30,60,90 g的空口咀嚼时间均差异有显著性意义(P0.05)。结果证实,牙齿移动后空口咀嚼时间变化规律和临床正畸牙移动疼痛规律一致,能够作为大鼠牙移动后口颌面部疼痛相关行为学反应之一。     

转矩作用对微植体矫治力系内收上前牙影响的三维有限元研究

目的研究转矩力的作用对于微植体矫治力系内收上前牙的影响。方法利用MIMICS软件和有限元软件ABAQUS,建立微植体矫治力系的有限元模型,并在该模型上计算分析有无转矩及转矩作用区域对中切牙和侧切牙移动趋势的影响。结果不加转矩时,中切牙和侧切牙都表现出舌向倾斜的趋势。在100g·cm转矩力的作用下,随着转矩作用区域的增大,中切牙的唇向移动趋势逐渐减小,侧切牙由舌向移动逐渐转为唇向移动。结论转矩能够有效改变牙齿的移动方式,如果转矩从中切牙之间开始向两侧远中方向逐渐减少,效果会更好。     

皮质骨切开辅助大鼠正畸牙齿移动有限元分析

目的仿真模拟大鼠皮质骨切开后正畸牙齿移动,分析切开手术对大鼠牙颌结构力学分布的影响。方法建立大鼠正畸牙齿移动三维有限元模型,模拟皮质骨切开手术,并根据加载方向及牙根部位对牙周膜及根周牙槽骨进行细分,计算磨牙与切开骨块初始位移及各细分区域内牙周膜、牙槽骨的应力、应变分布。结果上颌第1磨牙在正畸力作用下近中倾斜移动,最大位移集中于牙冠远中尖;皮质骨切开能增加牙槽骨块初始位移。牙周膜最大主应变集中于近远中颈部,最小主应变集中于远中根尖部;皮质骨切开对牙周膜应变的分布及水平有明显影响;皮质骨切开能够明显增加牙槽骨中应力水平,并使高应力区集中于牙根近中牙槽嵴。结论皮质骨切开能够改变正畸矫治力在牙齿及牙周组织中的分布,使其有利于局部牙槽骨改建,实现快速正畸牙齿移动。研究结果有助于从生物力学角度认识皮质骨切开辅助正畸牙齿移动机制。     

微种植支抗在安氏Ⅱ类Ⅰ分类错颌病例的应用及疗效观察

目的：讨论微种植支抗钉在安氏Ⅱ类Ⅰ分类错颌畸形病例中的应用及疗效.。方法对80例Ⅱ类Ⅰ分类错颌畸形病例治疗效果分析,矫治安氏Ⅱ类Ⅰ分类错颌畸形病例80例中均拔除四个第一前磨牙牙齿,试验组40例,采用双侧上颌第一磨牙与第二前磨牙间放置微种植支抗钉进行拔牙后的间隙关闭。对照组40例,采用双侧佩戴口外弓加强磨牙支抗,关闭拔牙间隙,比较分析其作用效果。结果(试验组)采用上颌双侧微种植支抗钉关闭间隙的病例38例,上切牙切缘平均内收6.2mm,对上前牙的压入疗效明显,对于露龈笑、牙槽骨高度失调改善明显,上颌第一磨牙未出现前移,(或控制在1mm以内)完成最大甚至绝对支抗的控制,均在6个月以内关闭拔牙间隙。另外2例患者因种植支抗钉周围炎,种植支抗钉脱落而失败。(对照组)40例患者,其中有25例患者在6个月成功关闭拔牙间隙,在上颌切牙切缘平均内收4.5mm.,同时上颌第一前磨牙前移2mm,对上前牙压入收效甚微。对于患者露龈笑,牙槽骨高度不调改善不明显。另外15例患者因依从性较差,不能按时佩戴口外弓装置而出现上颌第一磨牙旋转,支抗丧失。不能很好的利用拔牙间隙内收上前牙,前牙切缘内收均少于4mm.而且间隙关闭均超出六个月。统计学值<0.05。结论安氏Ⅱ类Ⅰ分类错颌畸形矫治过程中[1],微种植支抗钉的应用明显优于口外弓的使用,做为稳定的骨性正畸支抗,前者能更好的控制上颌磨牙,做到尽可能多的内收和压入前牙,矫治疗效满意,疗程短,微型化,操作简单灵活,并有经济性安全性兼容的优点。不依赖患者的配合。     

方丝弓托槽片段弓技术治疗牙及牙槽外伤11例

目的 探讨使用方丝弓托槽片段弓技术固定牙外伤及牙槽外伤的临床效果.方法 利用方丝弓矫治原理和矫治方法 对外伤性牙松动、牙脱落及牙槽骨骨折共11例,22颗患牙进行固定结扎.结果 20颗患牙成功固定,恢复正常,仅2颗失败.结论 方丝弓托槽片段弓技术治疗牙外伤及牙槽外伤,牙齿复位精确,咬合关系恢复佳,有利于牙周健康,是外伤性牙及牙槽损伤可靠的治疗方法 .     

正畸复合矫治弓丝力学性能的有限元分析

探讨高效能复合矫治弓丝(composite archwire,CoAW)应用于牙齿正畸中的选优研究,并对复合矫治弓丝在正畸中的临床应用,提供理论指导及选型标准.对复合矫治弓丝正畸过程的力学行为进行了有限元分析,得到了各个不同类型弓丝对LL2、LL3、LL56的作用力-位移曲线,并由此分析得出不同类型弓丝对于不同牙齿的正畸范围.     

基于有限元仿真的形状记忆聚合物弓丝初始正畸力分析

正畸治疗过程中,临床常用镍钛金属弓丝对人体存在潜在的毒性作用,且缺乏美观性;相比之下形状记忆聚合物（SMP）材料因其良好的力学性能、易成形、美观性,在正畸中受到越来越多的重视。而形状记忆聚氨酯（SMPU）作为一种典型的SMP材料,其在正畸治疗效果方面的研究尚不充分,所能提供的矫治力大小有待进一步探究。在正畸矫治力研究中,临床口内检测非常困难,有限元分析技术是目前最主要的研究手段。针对上述问题,基于Tobushi一维SMP本构方程,参照粘弹性材料标准线性模型构建了SMP材料的三维本构方程,并利用FORTRAN语言编写了可用ABAQUS调用的UMAT子程序;参照正畸临床数据,利用三维建模软件建立了包括牙齿、托槽、弓丝在内的三维有限元模型,以侧切牙、尖牙为研究对象,通过对弓丝施加不同形式的变形,得出SMPU弓丝形变量为3 mm时产生的初始正畸力大小为0.06～0.55 N。结果表明, SMPU弓丝提供的初始正畸力与临床认为的最佳正畸力相比略为偏小,适合正畸治疗的第一阶段;但SMPU材料的力学性能还有进一步提升改善的空间,在正畸领域具有较高的潜在应用价值。     

Schizophrenia in a North Swedish geographical isolate, 1900–1977. Epidemiology, genetics and biochemistry

Over 200 schizophrenic patients belonging to three major and interrelated pedigree complexes have been investigated over the past 30 years in a North Swedish geographically isolated population, presently numbering about 6,000. An intensive investigation of a number of biochemical correlates and genetic markers in a few selected families belonging to one of the major pedigrees has indicated new strategies for the current research program.
Schizophrenia, as defined operationally, is significantly associated with decreased activities of two enzymes (1) blood platelet monoamine oxidase, (2) plasma dopamine-β-hydroxylase, and (3) with the genetic marker Gc² (group specific antigen). Both enzymes are subject to genetic variation. A positive score for linkage between schizophrenia and low plasma DBH activity has been calculated, but, so far, available data are insufficient for discrimination between linkage and partial contribution of genetically controlled low plasma DBH to the pathogenesis of the disease. Alternatively, both mechanisms could be involved.
As a model for continued research, schizophrenia is explained as based on a double dominant-recessive genotype (Aabb), representing a vulnerability which in about 50 % of cases develops into clinical schizophrenia. It is suggested that the dominant mutation (A) operates on or affects MAO activity, and that the recessive genotype (bb) is instrumental in low variates of DBH activity and very likely such variates within the normal range of physiological variation. Moreover, it is suggested that the combined effects of MAO- and DBH-reduced efficiency on the metabolism of e.g. dopamine could be an essential pathogenic mechanism for the schizophrenic illness which is segregating in this population.     

The dominant diseases of modernized societies as omega-3 essential fatty acid deficiency syndrome: Substrate beriberi

About 1900, modern food selection and processing caused widespread $\text{epidemics}$ of the B vitamin deficiency diseases of beriberi and pellagra which, for genetic reasons, often expressed as different diseases ranging from bowel and heart disease to dermatoses and psychoses. But the B vitamins merely help convert essential fatty acids (EFA) into the prostaglandin (PG) tissue regulators and it now turns out that, through hydrogenation, milling and selection of w3-poor southern foods, we have also been systematically depleting, by as much as 90%, a newly discovered trace Nordic EFA (w3) of special importance to primates and sole precursor of the PG3(4) series, even as a concurrent fiber deficiency increases body demand for EFA. Since substrate EFA is processed by many B vitamin catalysts, an EFA deficiency will mimic a $\text{panh}$ypovitaminosis B, i.e., a mixture of $\text{substrate}$ beriberi and $\text{substrate}$ pellagra resembling vitamin beriberi and pellagra but exhibiting as even more diverse $\text{endemic}$ disease. This would consitute a second stage of the Modern Malnutrition and explain why some workers now hold the dominant diseases of modermized societies to be new, nutritionally based, pellagraform yet lipid-related and to range, once again, from heart disease to psychosis. It is an assumption that our dominant diseases are unrelated to each other or are merely revealed by our diagnostic acumen and therapeutic success; and that hydrogenating millions of tons of food oils annually, to destroy the rancidity producing w3-EFA, is safe for $\text{primates}$. Extensive beriberiform disease is reported here in 32 typical cases taken from medical practice which responds strikingly to linseed oil supplements (60% w3-EFA) in confirmation of identical results in Capuchins.     

The universal muscular chain reaction,muscle spasm,Torsions, ruptures and extravasations. Chameleons of pathology and some manifestations of simple muscular disorders

Most bodily functions require the coordinated actions of complementary and supplementary paired muscle groups. Where this essential muscular cooperation is lacking, hollow organs may burst and others become literally screwed up, giving rise to many similar spastic diseases such as Torticollis, Twisted ovarian cyst, Torsion of the Testis, Volvulus of the intestines, Varicose Veins, Megacolon, Aortamegaly, Scoliosis, Erb's Palsy, Peyronie's Disease, Main-en-Griffe, Undescended Foot (Pes Cavus), Talipes, Strabismus. Spasm is “panenepidemic” and unclassified examples of Torsion Dystonia and Dyskinesia really are as common as debt and taxes.     

'Very sore nights and days': the child's experience of illness in early modern England, c.1580-1720

Sick children were ubiquitous in early modern England, and yet they have received very little attention from historians. Taking the elusive perspective of the child, this article explores the physical, emotional, and spiritual experience of illness in England between approximately 1580 and 1720. What was it like being ill and suffering pain? How did the young respond emotionally to the anticipation of death? It is argued that children’s experiences were characterised by profound ambivalence: illness could be terrifying and distressing, but also a source of emotional and spiritual fulfilment and joy. This interpretation challenges the common assumption amongst medical historians that the experiences of early modern patients were utterly miserable. It also sheds light on children’s emotional feelings for their parents, a subject often overlooked in the historiography of childhood. The primary sources used in this article include diaries, autobiographies, letters, the biographies of pious children, printed possession cases, doctors’ casebooks, and theological treatises concerning the afterlife.     

Guidelines for the Validation and Use of Immunoassays for Determination of Introduced Proteins in Biotechnology Enhanced Crops and Derived Food Ingredients

Recent advancements in agricultural biotechnology have created a need for analytical techniques to determine introduced proteins in crops enhanced through modern biotechnology techniques. These proteins are expressed in plant tissues and may be present in food ingredients. Immunoassays are ideally suited for protein detection and may be used as both quantitative and threshold methods. Microplate ELISA and lateral flow devices are two of the most commonly used immunoassay formats for agricultural biotechnology applications. This paper provides general background information and a discussion of criteria for the validation and application of immunochemical methods to the analysis of proteins introduced into plants and food ingredients using biotechnology methods. It is the result of a collaborative effort of members of the Analytical Environmental Immunochemical Consortium. This collaborative effort represents the combined expertise of several organizations to reach consensus on establishing guidelines for the validation and use of immunoassays. Further, the paper offers developers and users a consistent approach to adopting the technology as well as aid in producing accurate and meaningful results.     

Ultracryotomy: development and application (with examples from the yeast cytology) (author's transl)

The preparation steps usually necessary for obtaining ultrathin frozen sections of biological material (chemical prefixation, enclosing, cryoprotective treatment, freezing, sectioning, and post-staining the sections for transmission electron microscopy) are submitted to a critical analysis. The application of cryo-ultramicrotomy, in particularly for cytochemical purposes, is reviewed. Fundamental considerations of chemical prefixation and poststaining are supported by examples from yeast cytology. Furthermore, the efficiency of the cryo-ultramicrotomy (electron optical resolution of ultrastructural details) is demonstrated on yeast cells and protoplasts.     

Hypo- und Hypermagnesämie aus kardiologischer Sicht

Zusammenfassung Eine Reihe pathologischer Zustände bedingen Magnesiummangel. Zustände mit Hypermagnesämie sind ebenfalls bekannt, doch wesentlich seltener. Für den Kardiologen beachtenswert ist, daß unter Therapie mit bestimmten Diuretica bei Herzinsuffizienz, bei Herzinfarkt, Kardiomyopathie, Digitalisintoxikation und bestimmten Herzrhythmusstörungen Hypomagnesämie beobachtet wurde. Leider kann in der klinischen Routine nur ein extracelluläres Magnesiumdefizit durch Serumbestimmungen gemessen werden; über Magnesiummangel einzelner Organe kann nichts ausgesagt werden. Hinweise für Magnesiummangel geben aber neben der Messung des Serumspiegels Anamnese, klinischer Befund, bestimmte EKG-Veränderungen wie auch evtl. Hypokalämie, ein Zustand, bei dem sich oft — besonders bei Aldosteronismus — parallele Veränderungen zeigten.Tierexperimente deuten darauf hin, daß infarktähnliche Läsionen unter Magnesiummangel entstehen, doch ob Herzinfarkt beim Menschen durch Magnesiummangel ausgelöst werden kann, ist noch ungeklärt. In Leichenherzen zeigte sich im Infarktgebiet neben Calciumakkumulation signifikanter Magnesiumverlust, wobei unklar blieb, ob sich Ursache oder Folge des Infarktes widerspiegelten. Falls ein ursächlicher Zusammenhang besteht, ist er im Myokardstoffwechsel selbst zu suchen, wie bei der Alkoholkardiomyopathie, wo myokardialer Magnesiummangel zumindest als pathogenetischer Teilfaktor anerkannt wird. Andererseits versucht man aber auch Beziehungen zwischen Atherosklerose, Blutgerinnung und Hypomagnesämie herzustellen, in der Meinung, daß Magnesiummangel auch über den coronaren Pathomechanismus des Herzinfarktes wirken könnte. Sicher scheint, daß gewisse EKG-Veränderungen und Herzrhythmusstörungen durch einen irritierten Magnesiumhaushalt bedingt sein können, da sie bei Gabe bzw. Entzug von Magnesium verschwinden. Daß Magnesiummangel die Glykosidtoleranz verringert, wird tierexperimentell bestätigt. Unter Hypomagnesämie bewirkt Acetylstrophanthidin eher und länger Rhythmusstörungen als ohne, außerdem lassen diese sich durch Magnesiumgaben eliminieren. Da in gewissen Fällen spontane und digitalisinduzierte Herzrythmusstörungen durch Magnesiuminjektionen beseitigt wurden, scheint Magnesium als Therapeuticum angebracht. Einsatz verschiedener Magnesiumsalze bei Angina pectoris, degenerativen Herzerkrankungen und Herzinsuffizienz ohne geprüften und offensichtlich gestörten Magnesiumhaushalt ist fragwürdig, weil keine eindeutigen klinischen Erfolgsbeweise vorliegen. Immerhin mag es aber larvierte, durch Serumbestimmungen nicht erfaßbare Mangelzustände geben. Allgemein erscheint es aus kardiologischer Sicht ratsam, den Magnesiumhaushalt zu überwachen und in entsprechenden Fällen auszugleichen, um möglichen Myokardläsionen oder fatalen Herzrhythmusstörungen entgegenzuwirken.     

Renal dysplasia and asplenia in two sibs

A family is reported in which two sibs, one male and the other female, both died within 24 hours of birth with enlarged polycystic kidneys. Postmortem histology in the second child showed gross renal dysplasia. In both children the pancreas was enlarged, nodular and cystic but the liver appeared macroscopically normal. In the second child, histological examination confirmed pancreatic fibrosis with cystic dilation of ducts, but showed portal fibrosis with bile duct proliferation in the liver.
This combination of findings is very reminiscent of those in a girl and her brother reported by Ivemark et al. (1959). The children reported here also showed absence or hypoplasia of the spleen, cardiac anomalies and other features of the Ivemark syndrome (Ivemark 1955), a quite different, usually sporadic, congenital disorder. It is suggested that the children described here have a distinct lethal congenital disorder, probably inherited in an autosomal recessive manner.     

HLA in North Colombia Chimila Amerindians

HLA-A,-B,-C,-DRB1 and -DQB1 alleles have been studied in Chimila Amerindians from Sabana de San Angel (North Colombian Coast) by using high resolution molecular typing. A frequent extended haplotype was found:HLA-A*24:02-B*51:10-C*15:02-BRB1*04:07-DQB1*03:02 (28.7%) which has also been described in Amerinndian Mayos Mexican population (Mexico, California Gulf, Pacific Ocean). Other haplotypes had already been found in Amerindians from Mexico (Pacific and Atlantic Coast), Peru (highlands and Amazon Basin), Bolivia and North USA. A geographic pattern according to HLA allele or haplotype frequencies is lacking in Amerindians, as already known. Also, five new extended haplotypes were found in Chimila Amerindians. Their HLA-A*24:02 high frequencies characteristic is shared with aboriginal populations of Taiwan; also, HLA-C*01:02 high frequencies are found in New Zealand Maoris, New Caledonians and Kimberly Aborigines from Australia. Finally, this study may show a model of evolutionary factors acting and rising one HLA allele frequency (-A*24:02), but not in others that belong to the same or different HLA loci.