上颌中切牙角度基台不同载荷的三维有限元优化分析

背景：口腔种植修复中,种植体中基台角度的优化设计对骨吸收有重要影响,同时患者的高用力也对骨质的吸收重建有着重要影响。 目的：利用Ansys Workbench 13.0软件对上颌骨前牙区进行优化设计模型,探讨中切牙角度基台不同载荷对皮质骨和松质骨应力大小的影响。 方法：建立圆柱状V形螺纹种植体的上颌骨骨块三维有限元模型,设定基台角度为0°,5°,10°,15°,20°、25°,30°,设定加载应力为90,105,120,135,150,165,180,195,210 N。在种植体上模拟中切牙咬合,在修复体正中进行颊舌向力学加载,观察基台角度和加载应力变化对颌骨Von Mises应力峰值的影响。 结果与结论：单因素影响下,以基台角度为变量逐渐增加时,在唇腭侧向加载中皮质骨和松质骨的Von Mises应力峰值增幅分别为60.63%和69.30%;以加载应力为变量逐渐增加时,在颊舌向加载中皮质骨和松质骨的Von Mises应力峰值增幅分别为68.74%和69.30%。在基台角度和加载应力交互作用下,当加载应力小于  150 N,同时基台角度小于25°时,对颌骨Von Mises应力峰值响应曲线的切线斜率位于-1至0之间。所以从力学分析看来,松质骨的应力大小更易受到基台角度和加载应力的影响,螺纹种植体最佳的基台角度设计应小于25°,咬合力应小于150 N。中国组织工程研究杂志出版内容重点：生物材料;骨生物材料; 口腔生物材料; 纳米材料; 缓释材料; 材料相容性;组织工程     

天然上颌中切牙与种植体应力规律的三维有限元分析

背景：生物力学相容性是保证种植体与骨结合后长期稳定并行使功能的必要条件,因此,了解上颌中切牙与其周围骨组织应力应变分布情况对种植义齿修复尤为重要。 目的：根据天然牙5种不同解剖分型,探讨上颌中切牙牙根与种植体的应力分布规律。 方法：根据天然上颌中切牙5种不同解剖分型,通过UGNX、ANSYS等软件建立种植体及周围局部结构的三维有限元模型(B1、B2、M1、M2、P1),对种植体施加与牙长轴的夹角成0°、30°、45°、60°、90°的100 N静态荷载力,分析5类上颌中切牙牙根与种植体的应力分布情况。 结果与结论：5种分型中,天然中切牙与种植体等效应力随着加载力角度的增大而增大,种植体上升趋势高于天然牙。天然牙等效应力最大值集中在B1,最小值在M1,而种植体等效应力最大值在M1,最小值在M2。天然牙牙根等效应力有2%-31%的差距,种植体等效应力有4%-21%的差距,种植体的应力分布区间小于天然牙牙根的应力分布区间。说明种植体与天然牙随着咬合力角度的增大与受力呈正比,种植体所能承受的咬合力小于天然中切牙。中国组织工程研究杂志出版内容重点：生物材料;骨生物材料; 口腔生物材料; 纳米材料; 缓释材料; 材料相容性;组织工程全文链接：     

TM种植体骨界面应力分布的有限元分析

背景：种植体形态是决定种植体骨界面应力分布的重要因素之一。探讨顺应人体正常颌骨解剖形态的TM种植体骨界面的应力分布特征对临床医生选择和设计种植体有指导意义。 目的：观察集中荷载作用下TM种植体及其周围骨组织应力分布的特征。 方法：通过逆向工程技术,将二维下颌骨CT图片转化为三维实体模型,并建立3种包含不同锥度的TM种植体真实下颌骨B/2类骨质的有限元模型,利用有限元技术研究两种加载方式下TM种植体骨界面应力分布特征。 结果与结论：垂直加载时,对于锥度较大的TM种植体周边密质骨承受较小的应力;斜向加载时,对于锥度较大的TM种植体周边密质骨和松质骨承受较大的应力;种植体颈部,密质骨上缘与种植体接触处和种植体底部松质骨出现明显应力集中现象,斜向荷载下种植体骨界面的应力分布显著高于垂直荷载下的应力分布。从1/2长度开始变化的TM种植体骨界面在垂直荷载下表现出较好的应力分布特征。     

Ⅱ类骨质下上颌窦区垂直骨高度不足时应用短种植体长度和直径的优化分析

背景：应用短种植体在上颌窦区种植后生物力学指标会有哪些变化？ 目的：建立包含上颌窦的Ⅱ类骨质真实上颌骨模型,观察Ⅱ类骨质下上颌窦区垂直骨高度为9 mm时应用短种植体的最佳的长度和直径范围。 方法：建立包含短种植体的上颌窦区Ⅱ类骨质的骨块三维有限元模型,设定短种植体直径为4~6 mm和长度为6~8 mm,分析直径和长度对颌骨的等效应力峰值。 结果与结论：垂直(颊舌)加载时,随着直径增加,皮、松质骨的等效应力分别下降26%(40%)和31%(45%),随着长度增加,皮质骨和松质骨的等效应力峰值分别下降8%(5%)和0(7%)。两种方式加载时下,当直径 >4.8 mm且长度 >7.5 mm时,颌骨的等效应力峰值对直径和长度的响应曲线曲率位于-1和0之间,变量直径比长度对颌骨的等效应力峰值的影响更明显。结果证实,短种植体的长度和直径的增加可以降低颌骨应力,尤其是直径的增加更有利于改善力学分布,当窦嵴距为9 mm应用短种植体时,直径应 >4.8 mm,长度应 >7.5 mm,可保证其稳定性。     

新型种植体骨界面Ⅰ型胶原的表达

背景：刘福祥教授自行设计的新型种植体在较短种植体长度上给出了较大骨接触面积,同时考虑到种植体的抗扭转能力、抗侧向力能力,种植体与骨弹性模量的匹配及加工和植入、修复的便易度。 目的：观察自主设计的新型种植体植入颌骨后种植体-骨界面Ⅰ型胶原的表达变化,探讨新型种植体与牙槽骨的骨结合能力。 方法：拔除成年狼犬双侧下颌前磨牙3个月后,于两侧拔牙位点牙槽骨分别植入新型种植体和圆柱状种植体各2枚。 结果与结论：随时间增加两组周围骨组织密度逐渐升高,新型种植体组圆盘结构间出现密度逐渐升高的影像组织。两组种植体-骨界面均有Ⅰ型胶原表达,均于术后4周达高峰,且新型种植体组术后2,4周Ⅰ型胶原平均灰度值均高于圆柱状种植体组(P < 0.05)。表明新型种植体植入颌骨后能够取得生物性成功,种植体-骨界面成骨较圆柱状种植体更快,更活跃,骨结合能力更强。     

种植体深度和加载方向对下颌骨应力分布影响的三维有限元分析

目的分析下颌骨种植体种植深度和加载方向对周围骨组织的应力分布影响，为临床种植应用提供参考。方法CT扫描一位第一磨牙缺失的健康女性下颌骨，运用MIMICS图像重建其几何结构，ADINA建立下颌骨及种植体平齐0mm、高于1mm、低于-1mm骨界面三种有限元模型，分析比较该模型在垂直和颊舌向两种加载方式下周围骨组织内的应力分布。结果两种加载方式下三种模型相比，最大应力出现的部位没有明显变化，但数值发生了很大变化，以低于骨界面-1mm模型数值最大，高于骨界面1mm模型最小。颊舌向与垂直向加载相比，三种模型均呈现颊舌向数值明显高的态势。结论CT扫描最大限度地忠实于个性化的解剖结构，种植体种植深度和加载方向对骨组织内的应力分布有重要影响，本文结果将为临床种植技术提供一定的理论参考。     

尼古丁对不同表面处理种植体骨结合的影响

背景：研究证实尼古丁会影响成骨细胞、破骨细胞、成纤维细胞和红细胞的活性。 目的：检测尼古丁对表面喷砂或酸蚀处理种植体植入后骨结合及骨保护素、骨形成蛋白2表达的影响。 方法：将24只SD大鼠随机均分为实验组和对照组,实验组大鼠每天2次背部皮下注射2 mg/kg尼古丁,对照组对应皮下注射等量生理盐水。2周后在两组大鼠胫骨近干骺端分别植入表面喷砂或酸蚀处理的钛种植体,实验组继续皮下注射尼古丁,对照组注射生理盐水。种植后第2,4周对种植体及其周围骨组织行CT、X射线、荧光定量PCR及苏木精-伊红染色观察。 结果与结论：与对照组相比,实验组骨结合程度及骨保护素和骨形成蛋白2表达明显下降(P < 0.05)。在尼古丁作用下,表面喷砂处理种植体组骨保护素和骨形成蛋白2表达、表面酸蚀处理种植体组骨保护素表达均随时间变化明显下调(P < 0.05),并且表面酸蚀处理种植体组植入2周时骨形成蛋白2表达高于表面喷砂处理种植体组(P < 0.05);X射线与CT结果提示,尼古丁干预对表面酸蚀处理种植体周围新生骨形成量和新生骨矿化程度的影响明显小于表面喷砂处理种植体。苏木精-伊红染色显示,两种种植体周围成骨细胞的数量与活性随时间变化均降低,但表面酸蚀处理种植体组效果好于表面喷砂处理种植体组。中国组织工程研究杂志出版内容重点：生物材料;骨生物材料; 口腔生物材料; 纳米材料; 缓释材料; 材料相容性;组织工程全文链接：     

动态加载下3种基台材料对上颌角度植入种植修复体周围骨应力的影响北大核心

背景:在口腔种植修复中,上颌前牙区单颗缺失的患者缺牙区常因不同原因导致牙槽骨吸收、缺损,为了避免植骨的风险,往往采用倾斜植入种植体的方式避开牙槽骨吸收区域,并使用角度基台恢复患者正常覆合覆盖关系,不同的基台材料传递咬合力时影响力在种植体及周围骨的大小及分布。目的:比较模拟动态加载下使用3种基台材料的种植修复体在3种植入条件下对周围骨应力峰值随时间变化关系的影响。方法:选取1例行上颌中切牙区种植修复患者的锥形束CT资料,运用Minics软件对颌骨进行切割,运用Solidworks 2018建立种植体、颌骨、角度基台(角度分别为0°,15°,25°,基台材料分别为纯钛、氧化锆、氧化铝)、中央螺丝、二氧化锆全瓷冠等模型,装配完成,以原上颌中切牙牙根方向为植入0°角,然后分别模拟腭向倾斜15°,25°植入,种植体螺纹均无暴露,按照不同植入角度分为0°组、15°组、25°组,分别进行动态加载,加载时间为0.2 s,得出各组各材料基台种植修复体周围骨等效应力峰值随时间变化的关系。结果与结论:①所有基台种植修复体在受咬合力时周围骨应力峰值分布一致,均位于种植体颈部骨皮质,各材料基台种植修复体周围骨应力上升幅度最快时间段均为0.025-0.05 s内,15°组骨皮质高应力值范围较0°组更大,25°组种植体骨皮质初始应力值明显高于其余两组,且加载结束后骨皮质残留较高应力值;钛基台种植修复体周围骨应力上升幅度最大,高应力值范围较为集中;②在15°组中,3种材料基台种植修复体周围骨应力峰值均位于种植体颈部,应力上升幅度钛基台种植修复体周围骨应力上升幅度较大但并不明显,高应力分布范围较为一致;25°组相较于其余两组应力高值较为集中,应力起始值高且变化幅度更大,其中氧化铝基台种植修复体周围骨应力在0-0.1 s内上升幅度最大,在0.2 s时氧化锆基台种植修复体骨等效应力峰值降为0,其余两种材料基台种植修复体周围骨内均残留较高应力;③结果提示,植入角度及基台材料的不同影响应力在种植体骨界面的分布,采用氧化锆材料基台的种植修复体各时间点骨应力均较为稳定。     

60Co放射及微量元素锌对钛种植体骨融合的影响

背景：前期实验证实补锌可以加速种植体的骨融合。目的：观察⁶⁰Co放射及微量元素锌对种植体骨融合的影响。方法：取成年雄性家兔36只,双侧胫骨近心端各植入1枚钛种植体,建立钛种植体动物模型,随机均分为4组,补锌组种植后24 h肌注10 g/L硫酸锌4 mg/kg,1次/d;对照组种植后24 h肌注9 g/L生理盐水4 mg/kg,1次/d;放射组于种植后第2,4,6天给予双侧胫骨近心段⁶⁰Co照射,15 Gy/d,同时种植后24 h肌注9 g/L生理盐水4 mg/kg,1次/d;放射补锌组于种植后第2,4,6天给予双侧胫骨近心段⁶⁰Co照射,15 Gy/d,同时种植后24 h肌注10 g/L硫酸锌4 mg/kg,1次/d。种植后1,4,12周利用显微镜观察种植体骨界面组织形态。结果与结论：在相同时间段内,与其他各组相比,放射组种植体周围成纤维细胞数量较多,纤维性结合较多,而骨性组织特别是成熟骨组织形成较少。在相同时间段内,与其他各组相比,补锌组种植体表面成骨细胞数量更多,骨性结合更多,在第4周时即可见成熟骨组织出现,说明补锌能在种植后早期(1-4周)即形成骨性愈合。放射补锌组在第4,12周时也较放射组产生更多骨性结合,说明即使在⁶⁰Co照射后,微量元素锌的补充仍可以促进种植体-骨融合。提示⁶⁰Co照射会延缓种植体骨愈合,放射治疗后适量补锌能够减轻其对种植体骨融合的不利影响。 中国组织工程研究杂志出版内容重点：生物材料;骨生物材料; 口腔生物材料; 纳米材料; 缓释材料; 材料相容性;组织工程     

不同形状种植体支持单端固定桥的三维有限元分析北大核心

背景:种植体的形状影响其生物力学表现,目前对种植支持式单端固定桥的研究多在相同形状种植体进行,对不同形状种植体支持的单端固定桥的比较分析较少。目的:利用三维有限元建模,分析圆柱形、锥形与膨胀式3种种植体支持的单端固定桥在下颌后牙区的生物力学特征。方法:分别建立圆柱形、锥形与膨胀式种植体支持单端固定桥及其支持组织的三维有限元模型,对单端固定桥轴向90°和颊舌向45°分别施加300 N的力,分析皮质骨、松质骨的von Mises应力及种植体-基台复合体的最大位移。结果与结论:①在轴向和颊舌向加载力下,3种模型皮质骨的最大应力峰值远大于松质骨,皮质骨的最大应力峰值均集中于近悬臂种植体远中颈部周围;②膨胀式种植体模型在皮质骨中的最大von Mises应力值最低,在轴向加载力下尤其明显,在松质骨中的von Mises应力值最高;③与轴向加载力比较,颊舌向加载力下3种模型皮质骨、松质骨的von Mises应力峰值及种植体-基台复合体最大位移均增大;在颊舌向加载力下,膨胀式种植体模型的种植体-基台复合体最大位移最小;④结果表明,膨胀式种植体支持的单端固定桥稳定性最好。     

The development of the ligament of the head of the femur

The hip joints of 30 human male and female fetuses and stillborns between 20 mm and 350 mm crown-rump length were studied by light microscopy. The ligament of the head of the femur developed in situ as a condensation of mesenchyme at the end of the second month of intra-uterine life (IUL), and was vascularized by branches of acetabular vessels early in the fourth month. In the majority of fetuses older than 5.5 months IUL, vessels in the ligament passed a short way into the femoral head within cartilage canals, to supply a small region around the fovea capitis. The remainder of the head was supplied by vessels in canals from around the upper part of the neck. The ligament changed from predominantly cellular to fibrous during the last 4 months of IUL. This increase in strength suggested significant mechanical functions in utero: limitation of adduction-flexion and opposition to postero-superior dislocation were the most likely.     

肱骨结节间沟形态在肱二头肌长头肌腱损伤中的作用

目的　提供详尽的肱骨结节间沟形态资料。方法　使用不同地区肱骨 80只 ,将结节间沟分为近侧水平段和远侧垂直段 ,用量角器和卡尺测量二段的长度及其移行处的角度 ;结节间沟的深度和宽度分五个部位测量 ;观察结节间沟的变异和异常。结果　结节间沟近侧段和远侧段的长度及移行处角度分别为 9.4mm、2 9.7mm和 119.9° ;总长度、深度和宽度分别为 39.2mm、0 .7mm和 2 .6mm ;结节上嵴出现率为 11.2 % ,内、外侧骨刺 16 .2 % ,钙化 45 %。结论　肱骨结节间沟的局部形态与肱二头肌长头腱损伤关系密切。     

Contribution to the study of the venous vasculature of the penis

The penile veins are thought to be responsible for some erectile disorders. The aim of this study was to describe the anatomy and function of these veins. The venous systems of 25 cadaveric penises were studied by various anatomic and histologic techniques. The superficial veins arising from the tegumentary layers drain into the superficial dorsal vein which in three-quarters of cases empties into the left great saphenous vein. The veins of the deep internal system, running below the deep fascia of the penis, emerge from the erectile bodies and can be divided into two systems, one anterosuperior and the other posteroinferior. The anterosuperior system comprises the veins of the glans which will form the deep dorsal vein the latter receives blood from the medial portion of the corpus spongiosum and from the free portion of the corpora cavernosum mainly via the circumflex veins. It ends in the pre-prostatic plexus. The posteroinferior system, issuing from the posterior portion of the erectile bodies, is composed of the bulbar, cavernous and crural veins which drain towards the pre-prostatic plexus and the internal pudendal veins. Anastomoses link the two networks, superficial and deep. Study of the structure of the veins of the deep system reveals the presence of muscular cushions, which we have shown to have adrenergic innervation. These findings are compared with those of the literature, which show variations which are mainly of number. The place of veins in the mechanism of erection is discussed.     

Adequate function of the cell: Interactions between the needs of the cell and the needs of the organism

The continuous maintenance of cell adequate function (cellular stress) is considered to be the main feature which characterizes the activity of a live cell. In accordance with the concept of cellular stress, the transition of the cell to the state of adequate funcitoning represents a dual commitment. The cell must function adequately to respond to the demands of the organism and to provide for its own needs. Thus, it is proposed that two systems exist for the regulation of the adequate function of the cell: one enabling the cell to respond to the demands of the organism, and the other providing for the needs of the cell itself. The hormonal system of the organism represents the first of these mechanisms, and I believe that another system exists for regulation of intracellular needs. Adequate function of the cell is determined by the regulative, controlling and defense mechanisms. The balance between the needs of the cell and of the organism should be a concern of physician, since it provides for the optimal function and health of the organism as a whole.     

Anatomy of the ulnar part of the lateral collateral ligament of the elbow

The lateral ulnar collateral ligament (LUCL) of the elbow has been illustrated variably in anatomy texts. The purpose of this investigations was to determine the percentage of specimens in which this structure is present, and to describe its anatomy and function. The LUCL was identified as part of the lateral capsulo-ligamentous complex in 17 of 17 fresh frozen cadaver elbows (P <.0001). The LUCL originates on the lateral epicondyle, blends with the fibers of the annular ligament as it arches superficial to it, then curves to insert on the tubercle of the supinator crest of the ulna. It is distinct at its insertion, but not at its origin where its fibers blend with those of the common extensor origin. The insertion is exposed in the interval created between (the deep surface of) the fascia of the supinator and its muscle fibers. The insertion can be palpated by applying a varus stress to the elbow. Cutting the ulnar fibers permitted posterolateral rotatory subluxation of the ulno-humeral joint and varus subluxation of the elbow. © 1992 Wiley-Liss, Inc.     

On the musculature of the gastro-intestinal tract of the guinea-pig

Summary The small intestine, caecum, colon and part of the stomach of guinea-pigs were studied by light microscopy, using semithin sections of plastic embedded specimens. The muscular coat is thicker in the duodenum than in the rest of the small intestine. The ratio between longitudinal and circular muscle is 1:4.6 in the duodenum and it increases regularly along the small intestine, to reach 1:2 in the terminal ileum. In the caecum, shape and sectional area of the muscle tissue were analyzed along the full length of the taeniae. In the caecal circular muscle there is a characteristic change in the arrangement of the muscle bundles from the regions in the centre of the haustrations to the regions of the grooves between haustrations or to those lying beneath a taenia. The functional significance of the taeniae is discussed in terms of an arrangement allowing reduction of the lumen of the organ (which at the level of the grooves between haustrations acquires a triangular outline) more efficiently than if the longitudinal musculature were spread over the entire surface of the organ. Haustrations are present also on one side of the wall of the ascending colon where there is no longitudinal muscle layer. In the descending colon the structure of the wall is examined in different functional states, namely in the regions between fecal pellets (constricted regions) and in the regions around a fecal pellet (moderately distended regions). The musculature increases considerably in thickness in the constricted regions (both muscle layers being actively contracted), while the mucosa and submucosa are thrown into prominent longitudinal folds. These folds produce occlusion of the lumen when the circular muscle has shortened by about 50%.     

Measurements of the perivascular PO2 in the vicinity of the pial vessels of the cat

The effects of halothane on caffeine-induced tension transients in functionally skinned myocardial fibers were investigated. Fiber bundles from mechanically disrupted rabbit right ventricular papillary muscles were mounted on a tension transducer. The fiber preparation was loaded with Ca²⁺; Ca²⁺ was then released by the use of caffeine (25 mM); and the area of the resulting tension transient was measured. Each preparation was sequentially transferred from control to test to control solution. The control solutions were equilibrated with 100% N₂, and the test solutions with a mixture of N₂ and various halothane concentrations. The preparation was exposed to halothane during the Ca²⁺ uptake or the release phase only, or during both Ca²⁺ uptake and release phases. The areas of the test tension transients were compared with those of the two control tension transients. It was found that halothane depressed the caffeine-induced tension transient either during the uptake phase or the combined-uptake-and-release phase but not during the release phase. The halothane-induced depression was dose-dependent, reversible, and comparable to the depression observed in intact isolated papillary muscles. We conclude that halothane could induce myocardial depression by inhibiting Ca²⁺ uptake by the sarcoplasmic reticulum.Supported by Research Grants HL 20754 and AM 17081 from the National Institutes of Health and a Research Starter Grant from the Pharmaceutical Manufactures Association Foundation. Halothane was supplied by Ayerst Laboratories, Inc.     

Architecture of the caudal vena cava wall of the dog at the level of the liver caudate lobe

The vascular segment of the caudal vena cava of the dog at the level of the caudate lobe was shown to be intimately related to hepatic tissue through the hepatic capsule and parenchyma. The tunica adventitia of the caudal vena cava was formed mainly by smooth muscle cells with collagen and elastic fibers arranged in bundles. The thin tunica media of the vein was also formed by smooth muscle cells, collagen and elastic fibers arranged in bundles. The tunica intima presented an elastic subendothelial network. The hepatic segment of the caudal vena cava showed a myoconnective architecture and propulsive characteristics in terms of its hemodynamic pattern.     

腹部皮瓣的微血管构筑

应用成人尸体，墨汁灌注，将腹将皮肤分为6个区．各区取组织块常规石蜡包埋，连续切片，在光学显微镜下对该部皮瓣血管网进行了观察，该皮瓣血管网分5层，即乳头层、乳头下层、真皮深层、浅筋膜层和深筋膜层。测量了各层血管网的网眼密度及其内径．讨论了皮瓣的微血管构筑及其临床作用．     

直肠表面动脉的形态学观测

目的观察直肠表面动脉的分支分布特点。方法随机选取成人尸体20具,婴幼儿尸体15具,行巨微解剖观察。结果上段直肠主要由乙状结肠直肠动脉的横支供血,在器官表面的分支形式多为环绕型;直肠壶腹主要由直肠上动脉的终支供血,其在器官表面的分支形式多呈主根须样;直肠颈主要由直肠下动脉和肛动脉供血,其在器官表面的分支形式可有鸦爪型、单支型、二叉型、三又型及“K”型等;上半直肠多为横行的环状分布,下半直肠多为纵行分布;各支间可存在吻合,方式为网型、直接及不规则型吻合。结论在上半直肠前壁和直肠颈后壁,存在无血管吻合区;直肠动脉在器官表面存在区域性配布的特点。