Non uniformity in the PDL: structure and function of the dense collar

摘要： 牙齿在整个生命周期中在高重复性咀嚼负荷下发挥作用。它们需要迅速适应食物， 不同的尺寸和大小，以实现有效的咀嚼过程。这种快速的适应 这种能力是由一种独特的软组织提供的，这种软组织将牙齿连接到牙槽骨，即牙周膜 （PDL）。因此，PDL对于正常的牙齿功能和生存至关重要。目前，有不同的 用于不同程度地恢复牙齿和牙槽骨结构的解决方案， 恢复PDL。该提案将为PDL的再生治疗建立一个平台。PDL是一个 不均匀的组织，我们最近确定了一个独特的结构，致密的胶原蛋白网络在最冠状部分， 并创造了“致密领”这个词。该区域由密集的短水平纤维组成， 与牙齿的自然漂移方向相对应的方向性偏好。我们最近的研究显示 与PDL中的分叉区域相比，致密轴环的刚度以及独特的成分。 因此，我们假设致密的颈领是整体牙齿稳定性的主要贡献者， 对致密的轴环结构的任何损害将影响整个PDL功能。为了验证这个假设，我们将 采取多学科的方法研究该组织的结构和功能及其在整个 PDL功能和牙齿稳定性。我们将生成ECM的基线和该区域的细胞概况， 使用定位蛋白质组学和质谱细胞术与PDL中的其他区域进行比较。我们将测量 使用高频AFM和使用原位加载的牙齿移动性来测量致密轴环的机械性能 我们将使用一种新的原位拉曼光谱和我们的microCT来解开胶原结构 基于软组织成像的方法。我们将联合收割机这些尖端的方法，利用不固定的 最小切片的样品，以使样品收集与其3D结构的背景。然后我们将测试 不同干预措施对致密领结构完整性对牙齿活动度的影响。我们将使用一个 改良牙周炎前模型和正畸牙移动小鼠模型，并比较其结构和 密领的力学性能达到基线。在最后一个阶段，我们将确定一种方法， 密集的衣领，以增加牙齿的稳定性。这一建议将决定密领在牙齿中的作用 稳定性以及致密领结构变化与PDL整体功能之间的相关性。最 重要的是，解开PDL内特定区域的结构和功能将为 结构性干预以加强该区域并控制整个PDL功能和牙齿稳定性。这 该提案将为不同牙科领域的范式转变奠定基础，如牙科学，牙科创伤， 牙周病学

ABSTRACT: Teeth function under high repetitive masticatory loads throughout lifetime. They need to quickly adapt to food in different sizes and consistencies in order to enable an efficient masticatory process. This quick adaptation capability is provided by a unique soft tissue that connects the tooth to the alveolar bone, the periodontal ligament (PDL). The PDL, therefore, is critical for proper tooth function and survival. At present, there are different solutions for restoring teeth and alveolar bone structure to different extents but no predictable methods exist for restoring the PDL. This proposal will establish a platform for a regeneration therapy for the PDL. The PDL is a non-uniform tissue, we recently identify a unique structure of dense collagen network at the most coronal part of the PDL and coined the term dense collar. This region is consists of dense, short horizontal fibers with a directionality preference that corresponds to natural drift direction of the tooth. Our recent studies show higher stiffness of the dense collar when compared to the furcation region in the PDL as well as unique composition. We therefore hypothesize that the dense collar is a central contributor to the overall tooth stability and therefore any impairment to the dense collar structure will affect the entire PDL function. To test this hypothesis we will take a multidisciplinary approach investigating the structure and function of this tissue and its role in the entire PDL function and tooth stability. We will generate a base line of the ECM and cellular profile of this region in comparison to other regions in the PDL using localized proteomics and mass cytometry. We will measure the mechanical properties of the dense collar using high frequency AFM and tooth mobility using an in-situ loading device and we will unravel the collagen structure using a novel in-situ Raman spectroscopy and our microCT based method for soft tissue imaging. We will combine theses cutting edge methodologies utilizing unfixed samples with minimal sectioning to enable sample collection with their 3D structural context. We will then test the effect of different interventions to the structural integrity of the dense collar on tooth mobility. We will use a modified pre-periodontitis model and orthodontic tooth movement in mice model and compare the structural and mechanical properties of the dense collar to the base line. In the last stage we will identify a method to strengthen the dense collar to increase tooth stability. This proposal will determine the role of the dense collar in tooth stability and the association between structural changes in the dense collar and overall PDL function. Most importantly, unraveling the structure and function of a specific region within the PDL will generate a platform for structural interventions to reinforce this region and control the entire PDL function and tooth stability. This proposal will lay the ground to a paradigm shift in different dental fields such as orthodontics, dental trauma, and periodontics.