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

美国牙科办公室最近的一项调查发现，每八个人中就有一个患有牙齿敏感。牙齿敏感是由于牙齿较软的内部称为牙本质，它包含大量微米级的小管，从牙齿外部延伸到中央的神经，受到各种刺激。这种接触会在吃或喝热、冷、甜或酸性的东西后引发剧烈的疼痛。大多数患者是女性和20岁至50岁之间的人，他们的牙床退缩或在家美白牙齿。最常见的治疗方法是在牙齿上涂抹氟化物凝胶、清洗剂或清漆，或使用封闭剂进行牙齿表面处理。在这个项目中，与BioAstra Technologies Inc.(BTI)合作，使用BTI开发的一种新配方，基于智能聚合物，将智能微粒悬浮在其中，作为治疗牙齿过敏症的“咬合膏”。为了达到这一市场，需要开发一种牙本质的体外模型，模拟牙本质的自然成分和微结构，以充分表征其材料封闭/穿透牙本质微管的能力。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，含有液体和非胶原蛋白。该方案的目的是利用牙本质的这些主要成分作为生物墨水，建立一个三维打印的牙本质模型。BTI的智能聚合物和微粒的咬合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。这些技术包括具有数字图像处理的扫描电子显微镜-能量色散光谱、共聚焦激光扫描显微镜和X射线计算机层析成像。总的来说，这些技术将允许量化应用BTI的生物材料后多孔性网络的孔隙率、孔径分布和曲折程度，并为我们提供关于它们作为消费者保健产品治疗牙齿过敏的潜在用途的信息。

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.**************