Quantitative image analysis of dentin microtubules occlusion using smart hydrogel-based paste in 3D printed biomimetic dentin for the treatment of teeth sensitivity ************

美国牙科诊所最近的一项调查发现，八分之一的人患有牙齿敏感症。牙齿敏感是由牙齿的较软的内部部分（称为牙本质）暴露于各种刺激引起的，牙本质包含大量从牙齿外部延伸到中央神经的微米小管。这种接触会在进食或饮用热的、冷的、甜的或酸的东西后引发剧痛。大多数患者是女性和20至50岁之间的人，他们有牙龈萎缩或在家做牙齿美白。最常见的治疗包括在牙齿上涂抹氟化物凝胶、冲洗剂或清漆，或用封闭剂进行牙齿表面处理。在这个项目中，与Bioastra Technologies Inc. (BTI)BTI开发的一种基于智能聚合物的新制剂，其中悬浮有智能微粒，被提议作为用于治疗牙齿过敏症的"咬合糊剂"。为了进入这个市场，需要开发一种模拟天然牙本质组成和微观结构的牙本质体外模型，以充分表征其材料闭塞/渗透到牙本质微管中的能力。牙本质是分布在I型胶原纤维支架中的羟基磷灰石矿物的纳米复合材料，具有流体和非胶原蛋白。该提案的目的是开发一种3D打印牙本质模型，使用牙本质的这些主要成分作为生物墨水来构建该牙本质模型。BTI的智能聚合物和微粒的闭塞特性将通过使用先进的成像技术和分析方法跟踪它们进入牙本质模型的小管来研究。这些技术包括扫描电子显微镜-能量色散光谱与数字图像处理，共聚焦激光扫描显微镜和X射线计算机断层扫描。总的来说，这些技术将允许在应用BTI的生物材料后量化多孔网络的孔隙率，孔径分布和曲折度，并为我们提供有关其作为治疗牙齿过敏的消费者保健产品的潜在用途的信息。

A recent survey by U.S. Dental Offices finds that one in eight people suffers from sensitive teeth. The tooth sensitivity is caused by the exposure of the softer, inner part of the tooth called dentin, which contains a large number of micrometer tubules running from the outside of the tooth to the nerve in the center, to various stimuli. This exposure triggers sharp pain after eating or drinking something hot, cold, sweet or acidic. Most sufferers are women and people between 20 and 50 years old who had receding gums or did at-home tooth whitening. The most common treatments consist in applying fluoride gels, rinses or varnishes onto the teeth, or tooth surface treatment with occluding agents. In this project, in partnership with Bioastra Technologies Inc. (BTI), the use of a new formulation developed by BTI, based-on smart polymers in which smart microparticles are suspended, is proposed as "occluding paste" for the treatment of teeth hypersensitivity. To reach this market, an in vitro model of dentin needs to be developed that mimic the natural dentin composition and microstructure to fully characterize the ability of their materials to occlude/penetrate into dentin microtubules. The dentin is a nanocomposite of hydroxyapatite minerals distributed in a scaffold of type-I collagen fibrils, with fluid and non-collagenous proteins. The objective of this proposal is to develop a 3-D printed dentin model using these main compositions of dentin as bioink to build this dentin model. The occlusion properties of BTI's smart polymers and microparticles will then be investigated by tracking them into the tubules of the dentin model using advanced imaging techniques and analysis methods. These techniques include the scanning electron microscopy-energy dispersive spectroscopy with digital image processing, confocal laser scanning microscopy and X-ray computed tomography. Collectively, these techniques will allow quantifying the porosity, pore size distribution, and tortuosity of the porous network after the application of BTI's biomaterials and provide us with the information about their potential use as consumer healthcare products for the treatment of teeth hypersensitivity.**************