Department of Chemistry "Ugo Schiff" and CSGI, University of Florence, Via Della Lastruccia 3, 50019 Sesto Fiorentino, Italy.
Department of Chemistry "Ugo Schiff" and CSGI, University of Florence, Via Della Lastruccia 3, 50019 Sesto Fiorentino, Italy.
J Colloid Interface Sci. 2018 Jan 1;509:123-131. doi: 10.1016/j.jcis.2017.09.001. Epub 2017 Sep 21.
Dental decay, asa consequence of exposure to acidic foods and drinks, represents one of the most important tooth pathologies. Recently, enamel and dentinal surface remineralization using hydroxyapatite nano- and microparticles has been proposed; however, commercial remineralizing toothpastes are quite expensive, mostly due to the high costs of hydroxyapatite. Hence, we propose a thermoresponsive hybrid nanocomposite material as filler for tooth defects. The use of thermoresponsive composite particles aims at filling exposed dentinal tubules in response to a change of temperature in the oral cavity. In addition, the presence of the organic matrix contributes to the occlusion of the dentinal tubules, therefore reducing the needed amount of hydroxyapatite.
Poly-N-isopropylacrylamide microgels containing different amounts of hydroxyapatite nanoparticles were prepared via radical polymerization in the presence of N-N'-methylenebisacrylamide as cross-linker followed by mechanical grinding. The nano- and microstructure of the hydrogels and their thermal behavior were studied via small-angle X-ray scattering (SAXS), scanning electron microscopy (SEM) and differential scanning calorimetry (DSC). Defected teeth were treated with a dispersion of nanocomposite microparticles to simulate toothpaste action.
The hydrogels maintain their structure and thermal responsiveness when loaded with an amount of hydroxyapatite nanoparticles up to 2.3%w/w. In addition, the lower critical solution temperature is not affected by the presence of the mineral particles. Exposed dentinal tubules on the surface of test tooth samples were successfully occluded after 15 cycles of treatment with a dispersion of nanocomposite microparticles alternated with washing steps.
由于暴露于酸性食物和饮料，龋齿是最重要的牙齿病变之一。最近，已经提出了使用羟基磷灰石纳米和微颗粒对牙釉质和牙本质表面进行再矿化；然而，商业再矿化牙膏非常昂贵，主要是由于羟基磷灰石的成本很高。因此，我们提出了一种热响应性混合纳米复合材料作为牙齿缺陷的填充物。使用热响应性复合颗粒的目的是在口腔温度发生变化时填充暴露的牙本质小管。此外，有机基质的存在有助于闭塞牙本质小管，从而减少所需的羟基磷灰石量。
通过自由基聚合在 N，N'-亚甲基双丙烯酰胺存在下制备含有不同量羟基磷灰石纳米颗粒的聚 N-异丙基丙烯酰胺微凝胶作为交联剂，然后进行机械研磨。通过小角 X 射线散射（SAXS）、扫描电子显微镜（SEM）和差示扫描量热法（DSC）研究水凝胶的纳米和微观结构及其热行为。用纳米复合材料微颗粒的分散体处理有缺陷的牙齿，以模拟牙膏的作用。
当负载的羟基磷灰石纳米颗粒量达到 2.3wt%时，水凝胶保持其结构和热响应性。此外，存在矿物质颗粒不会影响较低临界溶液温度。在用纳米复合材料微颗粒的分散体处理 15 个循环后，测试牙齿样品表面的暴露牙本质小管成功被堵塞，然后进行清洗步骤。
