正畸牙移动相关信号通路研究进展

<正>畸牙移动是在机械力的作用下,通过对牙周膜产生牵张或压缩的力来引起牙周组织在生理限度内的组织改建,从而达到牙齿移动、矫治畸形的目的。由于没有明显的年龄限制,正畸矫治在全球范围已变得越来越普遍。因此,相关的研究也日益增多。牙齿移动的生物学基础是正畸力作用于牙周组织激活一系列信号转导通路,进而引起牙周膜的修复改建。为指导临床、加速正畸矫治疗程提供新的思路,本文综述了近年来有关正畸牙移动相关信号通路的研究进展。发现最新的研究集中在MAPK信号通路,Wnt/β-catenin信号通路,PI3K/AKt/m TOR信号通路,BMP-2信号通路,Caspase-3介导的凋亡通路较多。但是正畸牙移动引起的牙周组织改建是一个多种生物力学信号转导通路相互调节相互作用的过程,对于上述信号通路之间的相互关系还有待于我们更进一步的探索。     

Critical conditions for pattern formation and in vitro tubulogenesis driven by cellular traction fields

In vitro angiogenesis assays have shown that tubulogenesis of endothelial cells within biogels, like collagen or fibrin gels, only appears for a critical range of experimental parameter values. These experiments have enabled us to develop and validate a theoretical model in which mechanical interactions of endothelial cells with extracellular matrix influence both active cell migration--haptotaxis--and cellular traction forces. Depending on the number of cells, cell motility and biogel rheological properties, various 2D endothelial patterns can be generated, from non-connected stripe patterns to fully connected networks, which mimic the spatial organization of capillary structures. The model quantitatively and qualitatively reproduces the range of critical values of cell densities and fibrin concentrations for which these cell networks are experimentally observed. We illustrate how cell motility is associated to the self-enhancement of the local traction fields exerted within the biogel in order to produce a pre-patterning of this matrix and subsequent formation of tubular structures, above critical thresholds corresponding to bifurcation points of the mathematical model. The dynamics of this morphogenetic process is discussed in the light of videomicroscopy time lapse sequences of endothelial cells (EAhy926 line) in fibrin gels. Our modeling approach also explains how the progressive appearance and morphology of the cellular networks are modified by gradients of extracellular matrix thickness.     

A method to fabricate mesoscopic freestanding polydimethylsiloxane membranes used to probe the rheology of an epithelial sheet

Details are presented for the formulation, fabrication, and mechanical characterization of mesoscopic freestanding polydimethylsiloxane (PDMS) elastomer membranes, 10.0 μm thick and 5.0 mm in diameter, used to probe the rheology of a living epithelial sheet. In what is described as a composite diaphragm inflation (CDI) experiment, freestanding PDMS membranes are utilized as substrates for the culture of a sheet of epithelial cells. Together, the cell layer and the PDMS elastomer form a composite diaphragm (CD) that is suitable for mechanical testing in an axisymmetric membrane inflation experiment. In order to distinguish the rheological behavior of the epithelial sheet from the mechanical response of the elastomer using inflation test data, freestanding PDMS membranes should exhibit a highly compliant yet mechanically invariant finite load-deformation response when subjected to multiple inflation cycles following intermittent periods of cell culture. Given these considerations, we describe a method for preparing freestanding PDMS elastomer membrane specimens that are optically transparent, tensed, and wrinkle-free. Surface modifications intended to facilitate cell culture, namely water vapor plasma and ultraviolet light treatments, were shown to dramatically stiffen the mechanical response of the membranes, rendering them unusable as CD substrates. In this study, only PDMS membranes with physiosorbed collagen demonstrated the mechanical compliance, fatigue resistance, and environmental stability necessary for reliable use in CDI experiments.     

In vivo determination of aluminum,cobalt, chromium,copper, nickel,titanium and vanadium in oral mucosa cells from orthodontic patients with mini-implants by Inductively coupled plasma-mass spectrometry (ICP-MS)

Miniscrews are used as orthodontic anchorage devices in the dentistry clinical practice but the in vivo metallic release from these structures has been not previously investigated. The aim of this study was to determine the content of Al, Co, Cr, Cu, Ni, Ti and V in oral mucosa cells of control subjects, patients under orthodontic treatment and with both, orthodontic treatment and miniscrew, in order to know the contribution of these mini-implants to the total metallic content. ICP-MS measurements revealed the following ascending order: Cr < Ni < Ti < Cu < Al, and Co and V were practically undetected. Significant differences in comparison to the control group were found for Cu in the orthodontic group, and for Ni in both, orthodontic and orthodontic + miniscrew groups. Potential correlations among metallic elements and with some clinical factors were also explored. These findings suggest that miniscrews do not increase significantly the metal release.     

Do soft drinks affect metal ions release from orthodontic appliances?

ObjectiveThe effect of orange juice and Coca Cola^® on the release of metal ions from fixed orthodontic appliances.Materials and methodsA continuous flow system designed for in vitro testing of orthodontic appliances was used. Orange juice/Coca Cola^® was flowing through the system alternately with artificial saliva for 5.5 and 18.5 h, respectively. The collected samples underwent a multielemental ICP-OES analysis in order to determine the metal ions release pattern in time.ResultsThe total mass of ions released from the appliance into orange juice and Coca Cola^® (respectively) during the experiment was calculated (μg): Ni (15.33; 37.75), Cr (3.604; 1.052), Fe (48.42; ≥156.1), Cu (57.87, 32.91), Mn (9.164; 41.16), Mo (9.999; 30.12), and Cd (0.5967; 2.173).ConclusionsIt was found that orange juice did not intensify the release of metal ions from orthodontic appliances, whereas Coca Cola^® caused increased release of Ni ions.     

髋臼粉碎性骨折治疗方法的选择与预后探讨

目的:研究髋臼粉碎性骨折采用骨牵引与手术治疗的疗效的比较。方法:将118例髋臼粉碎骨折患者分为骨牵引组(74例)和手术组(44例),分别进行比较。结果:骨牵引组解剖复位10例(13.5%)、满意复位26例(35.1%),自我感觉优8例(10.8%)、良24例(32.4%);手术组解剖复位9例(40.9%)、满意复位12例(54.5%),自我感觉优7例(31.8%))、良9例(40.9%)。结论:手术治疗髋臼粉碎性骨折疗效明显优于骨牵引。     

α-SMA与肿瘤发展相关性的研究

以小鼠的肝、肺组织的正常细胞与肝肿瘤细胞（Hepa1-6）、肺肿瘤细胞（LLC）为研究对象,通过CTFM（cell traction force microscopy）法测定了4组细胞系的牵引力;用荧光抗体染色技术比较了小鼠细胞的α-SMA蛋白在癌变前后的变化。实验发现：与小鼠正常细胞相比,在α-SMA的表达水平上,Hepa1-6细胞α-SMA的平均光密度减小了47.9%,LLC细胞下降了52.3%;而Hepa1-6细胞牵引力的均方根值减小了53.4%,LLC细胞减小了49.7%。这说明α-SMA的表达与牵引力的变化以及细胞癌变的过程是密切相关的。     

Finite element modeling of superelastic nickel–titanium orthodontic wires

Thanks to its good corrosion resistance and biocompatibility, superelastic Ni–Ti wire alloys have been successfully used in orthodontic treatment. Therefore, it is important to quantify and evaluate the level of orthodontic force applied to the bracket and teeth in order to achieve tooth movement. In this study, three dimensional finite element models with a Gibbs-potential-based-formulation and thermodynamic principles were used. The aim was to evaluate the influence of possible intraoral temperature differences on the forces exerted by NiTi orthodontic arch wires with different cross sectional shapes and sizes. The prediction made by this phenomenological model, for superelastic tensile and bending tests, shows good agreement with the experimental data. A bending test is simulated to study the force variation of an orthodontic NiTi arch wire when it loaded up to the deflection of 3 mm, for this task one half of the arch wire and the 3 adjacent brackets were modeled. The results showed that the stress required for the martensite transformation increases with the increase of cross-sectional dimensions and temperature. Associated with this increase in stress, the plateau of this transformation becomes steeper. In addition, the area of the mechanical hysteresis, measured as the difference between the forces of the upper and lower plateau, increases.     

Micro-CT监测尼古丁对大鼠正畸牙移动过程中牙周改建的影响

目的:探讨不同摄取量的尼古丁对大鼠正畸过程牙周改建的影响。方法:选择120只雄性Wistar大鼠并将其随机分为四组:A组-空白对照,B组-正畸模型,C组-正畸并0.01 mg/m L尼古丁给药,D组-正畸并1 mg/m L尼古丁给药。分别于实验开始后第1、3、7、14、21天通过Micro-CT和HE染色观察模型牙齿移动距离和牙周组织改变并通过ELISA实验检测IL-17的表达。结果:Micro-CT扫描显示:正畸建模组相对于空白对照组在牙移动距离、骨体积分数、骨密度等指标均有明显变化,变化最大幅度发生在D组,B、C两组之间的差异没有统计学意义(P0.05)。21天,D组移动距离达到0.80±0.06 mm,明显高于B、C组(P0.05)。相较于空白对照组(A组),B、C、D三组Micro-CT测量的骨体积分数、骨密度、骨小梁厚度均降低,D组骨密度值降至1108.36±8.86mg/cm3。HE染色结果显示:D组在21天时破骨细胞增多并出现牙根吸收陷窝伴牙周膜纤维排列混乱;ELISA检测显示B、C组IL-17的含量在第7天时达到峰值,D组则在14天含量最高。结论:高浓度的尼古丁可加速正畸牙齿的移动速度及牙槽骨吸收,增加牙周组织中的破骨细胞及IL-17表达水平。     

微型钛板联合颌间牵引钉内固定术治疗颌骨骨折疗效观察

目的:探讨微型钛板联合颌间牵引钉内固定术治疗颌骨骨折的临床效果及其在临床的安全性。方法:随机选取颌骨骨折患者共60例,将上述患者随机平均分成对照组与观察组。分别给予与单纯微型钛板坚固内固定治疗和微型钛板联合颌间牵引钉内固定术治疗方法。分析比较这两组患者4周内的临床治疗效果及安全性。结果:术后4周两组间临床治疗效果比较显示:采取微型钛板联合颌间牵引钉内固定术治疗的观察组治疗效果明显好于给予单纯微型钛板坚固内固定治疗的对照组。观察组总有效率为87%,对照组总有效率为53.3%,差异有统计学意义(P0.05).两组手术过程均顺利实施,患者术后均无严重并发症发生,术后恢复情况较好,经比较两组术后不良反应的差异无统计学意义(P0.05)。结论:微型钛板联合颌间牵引钉内固定术是治疗颌骨多发骨折有效安全方法。