Development of Novel High-aspect-ratio Nanofillers for Dental Composites

描述（由申请人提供）：本提案的目标是开发新型纤维状陶瓷纳米填充物，该填充物将显著优于牙科复合材料中使用的现有纳米填充物。迄今为止，与微填充复合材料相比，纳米填料，如二氧化硅或硅酸盐纳米颗粒，在机械性能和临床行为方面只提供了渐进式的改进。我们提出采用仿生和工程方法合成纤维状羟基磷灰石（HA）和碳化硅（SiC）填充剂用于牙科复合材料。使用这种材料的理由是：1)陶瓷纳米纤维和纳米板的机械强度与其直径或厚度的平方根成反比，并将在纳米尺度上达到最大值/理论值；2)荷载传递大致与纵横比成正比，直至最大值。这样的填料将更坚固，也可以在复合材料中承载更多的载荷。将低温等离子体（部分电离气体）应用于上述纳米填料的功能化或涂覆，以改善其分散性能和与树脂基体的界面结合。虽然使用硅烷的功能化是有限的，并且依赖于衬底材料，但等离子体功能化可以在不同的衬底上提供各种官能团。等离子体功能化的羟基磷灰石和碳化硅，以及商业陶瓷填料（对照），将被纳入树脂基体，以制造牙科纳米填充复合材料。将对复合材料的力学性能和耐久性以及纳米填料和复合材料的生物相容性进行评价。假设与现有纳米填料相比，表面改性的高纵横比陶瓷纳米填料具有更强的强度，可有效提高复合材料的力学性能和耐久性，并具有更好的生物相容性。这项工作将为开发新型纤维状陶瓷纳米填充物奠定开创性的基础，这些填充物用于牙科复合材料，具有更好的机械性能、耐久性和/或生物相容性。此外，在这个项目中获得的知识将有利于其他领域的研究，如硬组织工程和开发这些组织的替代材料/结构。龋齿仍然是牙科中的一个常见问题，恢复牙齿功能的主要治疗方法是使用惰性材料进行修复，例如牙科复合材料。现有的微填充和纳米填充牙体复合材料的龋病人群较多，力学性能较差，因此本研究具有重要的意义。

DESCRIPTION (provided by applicant): The objective of this proposal is to develop novel fiber-like ceramic nanofillers that will significantly outperform the existing nanofillers used in dental composites. To date, nanofillers, such as silica or silicate nanoparticles, have provided only incremental improvements in mechanical properties and clinical behavior as compared to microfilled composites. We propose to synthesize fiber-like hydroxyapatite (HA) and silicon carbide (SiC) fillers for dental composites using biomimetic and engineering approaches. The rationale for using such materials are: 1) the mechanical strength of ceramic nanofibers and nanoplates is in inverse proportion to the square root of their diameter or thickness and will reach the maximum/theoretical value in nanoscale; and 2) the load transfer is roughly proportional to the aspect ratio up to a maximum value. Such fillers will be much stronger and can also carry more loads in composites. Low temperature plasmas, partially ionized gases, will be applied to functionalize or coat the above nanofillers to improve their dispersion property and interfacial bonding to resin matrix. While functionalization using silane is limited and dependent on the substrate materials, plasma functionalization can provide a variety of functional groups on different substrates. The plasma functionalized HA and SiC, as well as commercial ceramic fillers (control), will be incorporated into the resin matrix to make dental nanofilled composites. The mechanical properties and durability of the composite and the biocompatibility of both nanofillers and composites will be evaluated. It is hypothesized that the surface modified high aspect ratio ceramic nanofillers will be much stronger, will effectively improve the composite mechanical properties and durability, and have better biocompatibility as compared to the existing nanofillers. The proposed work will lay the pioneering foundation for development of novel fiber-like ceramic nanofillers for dental composites with improved mechanical properties, durability, and/or biocompatibility. Moreover, the knowledge gained in this project will benefit research in other fields, such as hard tissue engineering and development of replacement materials/constructs for these tissues. Caries continues to be a common problem in dentistry and the primary treatment to restore the tooth to function is repair with an inert material, such as dental composites. The large population with caries and the inferior mechanical properties of the existing microfilled and nanofilled dental composites underscore the significance of the proposed research.