Biomechanical response of bovine temporomandibular joint disc to prolonged tensile stress

This study was designed to evaluate the influence of prolonged tensile stress on the viscoelasticity of the temporomandibular joint (TMJ) disc. Twenty discs from 10, 3-year-old cattle were used. Tensile stress of 1.5 MPa was applied to specimens from the discs for 10, 20, 40 and 60 min. Following the prescribed period of tension for creep, the specimens were removed from the tension device and any recovery observed for 20 min. In all specimens, strain increased at the onset of stress application and reached almost steady conditions after 5 min. Although, the strain became slightly larger when the creep time was longer, no significant differences were found in the strains between any two tests with different periods of creep. The residual strain increased significantly with creep duration, and similarly the degree of recovery decreased significantly. In 10- and 20-min creep tests, the residual strains were 0.1 and 1.0%, the specimens in 40- and 60-min tests revealed irreversible changes in length. It was concluded that continuous loading for >40 min causes creep damage in bovine TMJ disc, and that prolonged sustained tension affects the recovery of joint homeostasis.     

Oxygen reduction mechanism on corroded zinc

The mechanism of oxygen reduction on the as-polished and corroded zinc specimens has been studied using a rotating ring disc electrode (RRDE) system. On the as-polished surface, oxygen was reduced into two distinct steps. In the first step, about 44% of O₂ was reduced to H₂O₂ in a 2-electron reaction with the rest being reduced to OH^? in a 4-electron reaction. On the other hand, in the second step, with the increase of overpotential O₂ was almost exclusively reduced to OH^? in a 4-electron reaction. The first step reduction occurred on an air-formed oxide-covered surface at more positive potential than ?1.2 V vs. Ag/AgCl and the second step reduction (E < ?1.2 V) took place on a semi-uniformly active surface. On the corroded surface, the second step was not distinctly observed on the polarization curve, because reduction of the zinc corrosion products simultaneously took place around ?1.2 V. The O₂ reduction in the first step was inhibited by deposition of the corrosion products, though the ratio of amount of O₂ reduced to OH^? in a 4-electron reaction was larger than that on the as-polished surface. The mechanism of oxygen reduction is discussed on the basis of results obtained from the RRDE experiment.     

下颌前突患者下颌支矢状劈开截骨术后髁突运动轨迹的改变

目的:研究双侧下颌支矢状劈开截骨术对下颌前突患者髁突运动轨迹的影响。方法:采用ARCUSdigma下颌三维运动轨迹描记仪,以髁突运动中心为参考点,研究30例正常受试者、14例下颌前突患者手术前后开口、前伸和左右侧向髁突运动的轨迹。用SPSSV11.0统计软件包进行配对t检验和成组t检验。结果:下颌前突患者术前、术后、正常组左侧髁突的运动轨迹与右侧基本相同,左侧髁突与右侧的开口、前伸和侧方运动范围无显著性差异(P>0.05)。术前组与正常组髁突运动轨迹差别较大,术前开口、前伸和侧方运动范围均小于正常组(P<0.05);术后与正常组髁突运动轨迹接近,术后开口、前伸和侧方运动范围与正常组无统计学差异;术前与术后组髁突运动轨迹差别较大,术前开口、前伸和侧方运动范围均显著小于术后组(P<0.05)。结论:下颌前突患者手术后,随着术后正畸治疗及咬合自我调整,建立了正常的咬合引导关系,使下颌功能运动趋向正常。     

关节盘的组织结构及其生物学特性的研究进展

利用组织工程技术修复颞下颌关节盘缺损,是一种有效的方法。但是在修复设计上,必须正确地认识关节盘的组织结构及其生物学特性。下面就颞下颌关节盘的组织结构及其相关的基础研究进行综述。     

The effect of disc repositioning and post-operative functional splint for the treatment of anterior disc displacement in juvenile patients with Class II malocclusion

Purpose

To evaluate the effect of temporomandibular joint (TMJ) disc repositioning and post-operative functional splint for the treatment of anterior disc displacement (ADD) in juvenile patients with Class II malocclusion.

关节灌洗加透明质酸治疗不可复性关节盘前移位

目的　探讨颞颌关节不可复性盘前移引起的严重张口受限的非手术疗法。方法　对 5 9例不可复性盘前移 (包括 3 6例旋转移位 )的张口受限患者 ,行多次关节灌洗 ,配合木楔被动张口训练 ,透明质酸腔内注射治疗。结果　经 3次治疗后颞颌关节活动度明显增大 (P <0 .0 1)。基本无痛 ,无并发症。关节造影显示 :仅 3例关节盘部分复位。结论　该法操作简单 ,可反复进行 ,是治疗不可复性盘前移 (包括旋转移位 )引起张口受限的有效方法。     

传送盘回复式牵引成骨修复山羊上颌骨缺损的实验研究

目的：结合上颌骨的解剖生理特点，探讨采用传送盘回复式牵引成骨修复上颌骨缺损的可行性。方法：11只成年山羊．随机分为实验组和对照组。其中实验组9只，按固定期不同分为1、2、3个月组，每组3只；对照组2只。实验组山羊通过手术制作上颌骨前部节段性缺损，缺损长度12～14mm，平均大小12．7mm。同期制作缺损前方传送盘并使之后退．关闭缺损区，安置牵引器，通过牵引将传送盘回复原位。术后7天开始牵引，每天2次，持续15～18d，每次0．4mm．采用大体、影像学及组织学观察缺损区愈合情况。结果：传送盘牵引复位后，缺损区被新生骨修复，X线、三维CT及组织学检查显示，新骨形成良好，新骨形成方式符合传统牵引成骨的成骨方式。结论：传送盘回复式牵引成骨符合上颌骨的解剖特点．具有一定的临床可行性。     

山羊颞下颌关节盘细胞透射电镜观察

目的 用透射电镜的方法对两只1月龄健康山羊四只颞下颌关节盘的细胞及胶原结构进行了观察.方法 切取山羊双侧颞下颌关节盘,经组织学处理后行透射电镜观察细胞和胶原超微结构特征.结果 颞下颌关节盘由不均分布的细胞和胶原纤维组成,细胞有成纤维细胞样细胞和软骨细胞样细胞两种,其中成纤维细胞样细胞较软骨细胞样细胞占优势.成纤维细胞样细胞表现有细长的突起,核大,梭形或不规则形,细胞器较少.软骨细胞样细胞胞核呈圆形或椭圆形,周围少有电子透射区,细胞膜不明显,胞突少见.胶原纤维由平行排列的有周期性横纹特征的胶原原纤维组成.结论 颞下颌关节盘细胞有成纤维细胞样和软骨细胞样细胞两种,前者占优势,胶原原纤维表现有周期性横纹特征.这为颞下颌关节盘组织工程研究中细胞来源及表型分析奠定了一定基础.     

正常人开闭口位颞颌关节盘磁共振影像测量分析

目的:探讨正常人颞颌关节开、闭口位关节盘的形态变化特点及意义。方法:对9名健康男性大学生(21~23 岁),用超导磁共振仪,小视野线圈,分别采用左右侧卧位,拍摄双侧TMJ矫正矢状位质子加权开口位和闭口位不同层面的MRI影像,层厚3 mm,选取其中能清楚反映关节盘形态的166张图像用电子测量尺测量其关节盘的断面面积和周长。结果:正常人颞颌关节盘闭口位影像呈窄长形,开口位影像呈哑铃形;开口位影像断面面积明显大于闭口位面积(P<0101),断面周长二者间无明显差别(P>0105)。结论:正常人开口状态下颞颌关节盘形态较闭口时明显变粗,可能是该两种状态下关节内压变化的反映。     

星孢菌素对山羊颞下颌关节盘细胞自组装基体收缩的影响

目的 探索不同浓度星孢菌素对山羊颞下颌关节盘细胞自组装基体收缩性及细胞外基质合成的影响。方法 单层培养山羊颞下颌关节盘细胞至P3代,将5.5×10 ⁶个细胞在不同浓度（0、0.1、1、10、100 nmol·L ^-1）星孢菌素的完全培养基中分别接种于三维柱状琼脂糖井;每天每井换液,培养1周后观察自组装基体的形态变化;冰冻切片染色显示自组装基体细胞外基质及α-平滑肌动蛋白（α-SMA）的分布;酶联免疫吸附测定（ELISA）和Blyscan试剂盒检测基体细胞外基质含量的变化。结果 山羊颞下颌关节盘细胞接种4 h后,星孢菌素组和对照组细胞均在琼脂糖井内自组装,形成一圆盘状基体,之后变成球形。各组自组装基体在1周时天狼星红染色可见基体内大量胶原纤维分布;番红染色显示基体内纤维软骨样细胞明显分泌糖胺多糖（GAGs）;Ⅰ型胶原（ColⅠ）在免疫组织化学染色中呈强阳性;α-SMA免疫组织化学染色为弱阳性。星孢菌素组自组装基体内ColⅠ和GAGs较高,其中10 nmol·L ^-1组最明显（P<0.01）。结论 星孢菌素对自组装基体的收缩有一定干预效果,但不是非常突出;它更有利于细胞外基质的合成。