不同稳定咬合板厚度对可复性前移位患者颞下颌关节应力分布影响

目的 利用三维有限元方法比较双侧颞下颌关节(temporomandibular joint, TMJ)可复性前移位(anterior disc displacement with reduction, ADDwR)患者在佩戴两种不同厚度稳定性咬合板后紧咬时TMJ应力分布改变。方法 根据患者CT、MRI影像数据,依次构建ADDwR患者牙尖交错位(工况1)与戴3、5 mm稳定咬合板咬合(工况2、3)时共3个TMJ有限元模型。分别给予3种工况中的下颌骨施加最大肌力60 s,之后对各工况中关节窝和髁突软骨表面、关节盘表面及双板区的最大等效应力进行评估。结果 各工况左侧TMJ内各结构等效应力均大于右侧。戴3 mm咬合板后,双侧关节盘均未发生复位,关节盘应力仍旧集中在后带及双板区,双侧关节软骨表面应力显著增加;戴5 mm咬合板后,右侧关节盘复位,关节盘最大应力位于中间带,关节软骨和双板区等效应力降低约40%,左侧关节盘未复位,关节窝软骨和双板区等效应力下降约6%。结论 ADDwR患者佩戴不同厚度咬合板,TMJ内应力及其分布模式均发生改变;5 mm稳定性咬合板可以减小ADDwR患者关节窝软骨及双板区...     

颞下颌关节负荷与颞下颌关节病

颞下颌关节负荷与其正常生理功能和某些疾病的形成关系密切。本文就负荷与颞下颌关节改建、生长发育、致病机制及临床治疗方法之间的相互作用进行了比较全面的论述，旨在深入认识颞下颌关节负荷的临床意义。     

颞下颌关节紊乱综合征患者人格研究

本文报告了80例颞下颌关节乱综合征(TMJDS)患者经中国版 MMPI 测定,并与73例健康人及27例确诊的神经症病人人格测定结果比较,发现 TMJDS 患者多为神经质型个性,对躯体疾病呈过度反应,偏异个性特点以 Hs,Hy 值呈现高峰,但仍属非病理性的。从本组 TMJDS 平均年龄(24.16±4.85)及病程不长看,其个性偏异似非继发于疾病。     

颞下颌关节的观测

本文在２０９具成年标本上对颞下颌关节的下颌窝、下颌头、关节盘及关节囊进行了观测;对颞下颌关节的运动及弹响机制进行了讨论。     

正畸减数患者后牙前移对颞下颌关节应力影响的三维有限元分析

背景：颞下颌关节紊乱病与颞下颌关节内有高应力密切相关。减数拔牙后伴随着磨牙位置的改变,建立新的咬合关系往往会导致颞下颌关节内应力环境发生改变。目的：在牙尖交错位时,利用三维有限元模型分析正畸减数拔牙后不同程度磨牙前移下颞下颌关节的应力分布。方法：选择在山东青岛市市立医院口腔正畸科就诊的正常牙合患者1例,收集其锥形束CT和MRI数据,分别建立减数前、减数后上下磨牙前移1/3拔牙间隙(拔除4颗第二前磨牙)及减数后上下磨牙前移2/3拔牙间隙(拔除4颗第二前磨牙)的有限元模型,通过建模软件分析牙尖交错位时颞下颌关节各部位的应力分布。结果与结论：(1)减数前后模型中髁突、关节盘、骨关节窝的受力分布基本一致,髁突的应力主要分布于髁突的前部及顶部,关节盘的应力主要分布于关节盘的中带及外侧,颞骨关节窝的应力主要集中分布在关节窝的前部及顶部。与减数前相比,减数后模型中髁突、关节盘及关节窝的等效应力值减小;正畸减数拔牙后,上下磨牙前移1/3拔牙间隙模型中髁突及关节盘的等效应力值小于上下磨牙前移2/3拔牙间隙模型。(2)从生物力学角度上讲,正畸减数拔牙可以降低颞下颌关节的应力,进而提供良好的生物力学环境。     

颞下颌关节力学创伤的分子生物学研究

人们对颞下颌关节的生物力学适应性变化和疾病的生物学进程还了解甚少，而现代先进技术已提供方法允许我们对颞下颌关节疾患的发病机制作深入的研究。本综述调查了目前从分子生物学角度所认识的颞下颌关节组织对压力的适应性和病理性变化，希望可以增强了解复杂的颞下颌关节疾病的生物学创伤进程，并引导增加对颞下颌关节疾患的诊断和治疗途径。     

颞下颌关节韧带的断层影像解剖研究

目的：通过cT和MRI扫描,明确颞下颌关节韧带的形态、结构及其断层影像解剖特点。方法：选取60名健康志愿者分别行颞下颌关节CT、磁共振检查,观察颞下颌关节韧带的断层影像解剖特点。结果：颞下颌关节在cT图像中显示韧带呈等密度影,而钙化的韧带呈高密度影;在磁共振T1WI和T2WI图像中,翼下颌韧带、蝶下颌韧带、茎突下颌韧带、颞下颌韧带、下颌锤骨韧带（关节盘锤骨韧带）均显示为结构清晰的低信号影像,骨皮质在T1WI及T2WI图像中均显示为结构清晰的低信号影像,骨髓质均显示为结构清晰的高信号影像。结论：CT、磁共振成像可清楚地显示颞下颌关节韧带的断层影像解剖结构。     

颞下颌关节的生物力学

颞下颌关节是人体最为复杂,精细的关节之一,具有负重的功能,关节软骨是具有低渗透性的多孔粘弹性介质,生理状态下在软骨内部存在胶原－蛋白多糖－水凝胶网状结构应力缓冲系统。关节盘是特殊类型的结缔组织,不属纤维软骨,是髁突和关节窝之间的应力集中缓冲器。关节盘后组织具有高度的顺应性,在关节运动中发挥容积补偿作用,关节外侧壁是囊－韧带结构的复合体,拉伸强度和拉伸刚度较弱,长期的口腔副功能易使结构处于超负荷状态     

颞下颌关节三维动态磁共振成像研究及生物力学分析

目的通过在多层面二维动态MR成像上获取颞下颌关节组织的运动数据,构建颞下颌关节的三维动态模型,并进行初步生物力学分析。方法 MRI检查采用GE Signa 1.5T TwinSpeed超导型磁共振扫描仪。选取2例无症状男性志愿者行颞下颌关节MRI检查,将图像数据导入Mimics软件,构建颞下颌关节的三维模型,动态分析张口幅度和关节盘横径的量化关系。结果建立的颞下颌关节三维动态模型清晰显示三维动态盘髁关系及关节盘在动态过程中的形态变化;志愿者1张口/关节盘横径拟合直线为:y=-0.03x+14.44,相关系数R2=0.591,志愿者2相关拟合直线为:y=-0.061x+13.48,相关系数R2=0.306,志愿者张口位置与关节盘横径变化具有直线趋势,关节盘横径随着张口幅度的加大而呈现减小的趋势,颞下颌关节盘对于髁突的包绕程度与张口幅度呈反比。颞下颌关节盘纵径厚度在张口活动中后带外份及中带内份的变化幅度最大。结论通过颞下颌关节二维动态MR成像数据可构建三维动态模型立体动态地观察颞下颌关节运动,可直观、准确显示颞下颌关节盘髁关系,可作为颞下颌关节二维静态MR成像的有益补充,弥补常规MRI检查的局限。     

颞下颌关节的断层影像解剖学研究

目的：为颞下颌关节疾病的诊疗提供解剖学基础。方法：选用成人尸体头颈部标本15例，分别制成冠状、矢状、横断层标本。在经颞下颌关节层面上，观察颞下颌关节及其周围结构的解剖学关系，用游标卡尺测量关节盘的厚度。结果：冠状、矢状和横断层解剖可分别显示颞下颌关节的位置、毗邻关系及结构特点，冠状解剖可确定关节盘的位置，矢状解剖有利于关节脱位的诊断。关节盘最厚处4．02mm，最薄处1．32mm。结论：颞下颌关节的断层影像解剖对颞下颌关节疾病的影像诊断和内窥镜治疗具有重要的指导作用。     

不同牙 合 位时翼外肌对颞下颌关节盘的生物力学影响

目的　研究在牙尖交错位和最大张口位时可复性关节盘前移位中翼外肌对关节盘的生物力学影响及两牙合 位之间的差异。 方法　对已经建立的可复性关节盘前移位的颞下颌关节数字化仿真模型,在不同牙合 位时进行翼外肌加载,通过三维有限元的方法进行生物力学分析。 结果　最大张口位时,关节盘应力集中区较牙尖交错位时向前外侧移动,集中于关节盘中间带偏外侧区;关节盘中间带与关节盘后带之间存在明显位移差,形成位移撕裂带,而在牙尖交错位时则无类似位移差现象。 结论　在可复性关节盘前移位中,最大张口位时翼外肌可导致关节盘中间带偏外侧区的应力集中,在关节盘中间带形成位移撕裂带,导致此区域变薄、穿孔甚至撕裂。     

Comparison of reference points in different methods of temporomandibular joint imaging

PurposeConventional radiography is a well-established method for imaging of the temporomandibular joint (TMJ) structures. However, the dental computer tomography becomes more important for the visualization of teeth in the jaw-bone. The applicability of dental computer tomography for the visualization of the TMJ it not yet been proven. The aim of the study was to identify TMJ structures using reference points with the magnetic resonance imaging (MRI) and the computed tomography (CT).MethodsIn order to compare the visualization and measurement of the TMJ a total of eight human cadaver heads was examined with CT and MRI and analysed using reference points.ResultsIn both imaging techniques the selected reference points and distances are well definable and allow objective evaluation of anatomical structures. The CT images display a clearly better contrast to noise ratio than the MR images. The distance measurement of different width and length showed significant correlation of both images techniques.ConclusionsIn TMJ diagnostics, maximum information could be obtained using both imaging techniques together due to synergistic effects.     

In vivo prediction of temporomandibular joint disc thickness and position changes for different jaw positions

Temporomandibular joint disorders (TMD) are common dysfunctions of the masticatory region and are often linked to dislocation or changes of the temporomandibular joint (TMJ) disc. Magnetic resonance imaging (MRI) is the gold standard for TMJ imaging but standard clinical sequences do not deliver a sufficient resolution and contrast for the creation of detailed meshes of the TMJ disc. Additionally, bony structures cannot be captured appropriately using standard MRI sequences due to their low signal intensity. The objective of this study was to enable researchers to create high resolution representations of all structures of the TMJ and consequently investigate morphological as well as positional changes of the masticatory system. To create meshes of the bony structures, a single computed tomography (CT) scan was acquired. In addition, a high‐resolution MRI sequence was produced, which is used to collect the thickness and position change of the disc for various static postures using bite blocks. Changes in thickness of the TMJ disc as well as disc translation were measured. The newly developed workflow successfully allows researchers to create high resolution models of all structures of the TMJ for various static positions, enabling the investigation of TMJ disc translation and deformation. Discs were thinnest in the lateral part and moved mainly anteriorly and slightly medially. The procedure offers the most comprehensive picture of disc positioning and thickness changes reported to date. The presented data can be used for the development of a biomechanical computer model of TMJ anatomy and to investigate dynamic and static loads on the components of the system, which could be useful for the prediction of TMD onset.     

Influence of unilateral disc displacement on the stress response of the temporomandibular joint discs during opening and mastication

The temporomandibular joint plays a crucial role in human mastication acting as a guide of jaw movements. During these movements, the joint is subjected to loads which cause stresses and deformations in its cartilaginous structures. A perfect balance between the two sides of the joint is essential to maintain the physiological stress level within the tissues. Therefore, it has been suggested that a derangement of the joint is a contributing factor in the development of mandibular asymmetry, especially if problems of the temporomandibular joint start in childhood or adolescence. To analyze the movement of the mandible and the stresses undergone by the discs, two finite element models of the human temporomandibular joint including the masticatory system were developed, one corresponding to a healthy joint and the other with a unilateral anterior disc displacement with their movement controlled by muscle activation. A fibre-reinforced porohyperelastic model was used to simulate the behaviour of the articular discs. The stress distribution was analyzed in both models during free opening and closing, and during the introduction of a resistant force between incisors or molars. It was found that a slight unilateral anterior disc displacement does not lead to mandibular asymmetry but to a slight decrease of the maximum gape. With the introduction of a restriction between incisors, the maximum stresses moved to the anterior band in contrast to what happened if the restriction was imposed between molars where maximum stresses were located more posteriorly. Finally, the presence of a unilateral displacement of the disc involved a strong change in the overall behaviour of the joint including also the healthy side, where the maximum stresses moved to the posterior part.     

原发性失眠患者大脑结构磁共振成像研究

对原发性失眠患者大脑灰质结构异常的脑区进行综述,主要包括海马、丘脑、前额叶和扣带回。从目前的研究成果来看还没有一个关于原发性失眠神经病理学的一致报道,然而这些分歧可能会激发一个更加结构化和系统化的失眠症神经影像学研究方法,为进一步探索原发性失眠的病理生理机制提供一些新的视角。 【关键词】原发性失眠;结构磁共振成像;综述     

基于深度学习技术的磁共振成像研究进展

磁共振（MR）成像是当前应用于临床医学诊断的重要医学成像手段之一。如何缩短扫描时间进行快速成像一直以来都是MR成像领域中的热门研究问题。近年来,随着深度学习的兴起和快速发展,深度学习被广泛应用于医学图像处理领域中。目前基于深度学习的MR成像方法作为MR成像的新兴方向,相应的研究已取得了一系列进展。本文对几种常见的基于深度学习的MR成像方法进行归纳和简要分析,并对其研究前景进行了展望。     

膝关节内侧半月板突出与后根部损伤相关性的MRI分析

背景：半月板根部损伤是半月板突出的重要原因。近年来,国外有许多关于半月板根部损伤和半月板突出关系的研究报道,而国内暂无相关的报道。 目的：探讨膝关节内侧半月板突出与内侧半月板后根部损伤的相关性。 方法：回顾性分析84例具有膝关节内侧半月板突出征象患者的MRI及关节镜表现,将半月板突出长度≥ 3 mm或半月板突出长度/半月板最大径≥10%定义为严重突出,采用卡方检验分析两种测量方法下的内侧半月板突出与后根部损伤之间的相关性。 结果与结论：MRI显示内侧半月板严重突出(半月板突出长度≥3 mm或半月板突出长度/半月板最大径≥10%)与关节镜检查显示半月板后根部损伤具有显著相关性(P < 0.05),比值比及95%可信区间分别为25.04 (3.07-204.44),6.96(1.38-35.19)。结果可见膝关节内侧半月板严重突出与内侧半月板后根部损伤密切相关,是半月板根部损伤的重要特征。     

基于功能磁共振图像转换在阿尔茨海默症分类中的应用

为了能识别阿尔茨海默症（AD）早期症状,提出一种改进的3DPCANet网络模型,并结合患者功能磁共振成像（fMRI）转换,对AD不同阶段患者进行分类。首先预处理患者的fMRI,并对预处理后的图像进行局部一致性（ReHo）图像转换;然后采用改进的3DPCANet模型对fMRI转换后的图像进行特征提取;最后使用支持向量机进行分类。实验结果显示,改进后的3DPCANet模型可以对fMRI转换后的图像提取有效的分类特征,其中,晚期轻度认知障碍与AD、主观记忆衰退与AD、主观记忆衰退与早期轻度认知障碍的分类准确率分别达到90.00%、88.89%、88.00%,验证了本方法的有效性和可行性。     

基于静息态功能磁共振形态学腰椎间盘突出症慢性下肢痛模型大鼠的实验研究

【摘要】目的:基于静息态功能磁共振（RS-fMRI）技术和疼痛行为学技术,观察腰椎间盘突出症（LDH）慢性下肢痛模型大鼠脑结构及功能改变的特点,揭示LDH慢性下肢痛的脑机制。方法:选用6~8周龄健康的SD雄性大鼠24只,体质量（250±20） g,采用随机数字表法分为3组:正常组、假手术组、模型组,模型组采用自体髓核移植法建立LDH慢性下肢痛大鼠模型。各组分别于建模前0天、建模后第2、7、14、21、28天进行大体行为学观察、机械痛阈值测定、热痛阈值测定。每组随机选取4只大鼠分别于建模前0天、建模后第14、28天,利用Bruker公司7.0T核磁收集BOLD数据,采用局部一致性（ReHo）、分数低频振幅（fALFF）方法处理BOLD数据,对所得数据进行统计学分析。结果:（1）3组大鼠建模前机械缩足反射阈值（PWT）和热缩足反射潜伏期（TWL）比较差异无统计学意义（P>0.05）;假手术组建模后各时间点PWT和TWL与正常组比较,差异无统计学意义（P>0.05）;模型组大鼠建模后各时间点PWT和TWL与正常组、假手术组比较,差异有统计学意义（P<0.05）。（2）3组大鼠不同时间点脑结构区域比较存在交互作用,差异有统计学意义（P<0.05）。脑区图结果显示ReHo值存在显著差异的脑区有:左室周灰质、右纹状体;fALFF值存在显著差异的脑区有:右纹状体、左嗅球、双侧小脑分子层。结论:（1）大鼠采用自体髓核移植法进行LDH建模后,机械痛阈值和热痛阈值明显降低,出现痛觉过敏反应,提示LDH慢性下肢痛大鼠建模成功;（2）LDH慢性下肢痛模型大鼠静息态下某些脑区功能活动有明显改变,可能与慢性疼痛的发生和维持有关。     

Examination of joint space by magnetic resonance imaging in anatomically normal knees

The medial and lateral knee joint spaces of 184 patients who had anatomically normal knees were measured by using magnetic resonance imaging (MRI) method. The findings were compared according to age, sex, height, and body mass index changes of the individuals and the mean values of medial and lateral knee joint spaces were calculated in every group. The results show that in an anatomically normal population, all the individuals have larger lateral knee joint spaces than medial knee joint spaces. The patients lose knee joint space regularly with increasing age. Children have larger knee joint spaces than adults. Men have larger knee joint spaces than women. The knee joint space size of the patients increase regularly with increasing height up to 180 cm. The patients, who are taller than 180 cm do not show any marked difference in joint space size, when compared with the patients whose heights differ in between 171–180 cm. Knee joint space size is not related to the body mass index of the individual. © 1996 Wiley-Liss, Inc.