Dynamic monitoring of refractive index change through light-activated dental fillings

通过光激活牙科填充物动态监测折射率变化

• 批准号: EP/E026257/1
• 负责人: William Palin
• 金额: $ 25.2万
• 依托单位: University of Birmingham
• 依托单位国家: 英国
• 项目类别: Research Grant
• 财政年份: 2007
• 资助国家: 英国
• 起止时间: 2007 至 无数据
• 项目状态: 已结题
• 来源: https://gtr.ukri.org/projects?ref=EP%2FE026257%2F1
• 关键词: Dynamic; monitoring; refractive; index; change

The majority of dental patients prefer filling materials that match the aesthetics of their natural teeth. However, the durability of large 'white'-fillings (resin-based composites; RBCs) is generally considered to be inferior to the non-aesthetic 'silver'-filling types (dental amalgams). This may relate to the increased number of technique-sensitive application steps in addition to any inherent material shortcomings of RBCs.Modern RBC filling materials are supplied in a paste form. They are moulded directly by the dentist in the tooth cavity and subsequently set to a rigid material 'on command' with a high-intensity blue light. However, the RBC filling material has a limited depth of cure (approximately 2mm) and therefore the dentist must use multiple (incremental) layers to fill large cavities, unlike the use of dental amalgam whereby the cavity can be filled in bulk, reducing technique sensitivity, procedure time and cost. Consequently, the development of RBCs with improved depth of cure is highly desirable which may improve the shortcomings of such materials and ultimately improve its clinical success in order to benefit the patient community.There remain many unanswered questions relating to the change in optical properties of RBC filling materials as they harden under high-intensity light, which may provide a greater insight into the setting reaction to ultimately improve the depth of cure. By altering the components of the RBC, which include a resin matrix filled with reinforcing ceramic particles, it is possible to change the extent with which the curing light is transmitted through the material. This unique proposal offers, for the first time, the capacity to measure the change in optical properties throughout the hardening reaction of RBC materials, using optical coherence tomography (OCT). As the RBC hardens, the resin component becomes more dense and shrinks. Consequently the refractive index of the resin component increases (a property which changes the speed of light through the material). As the refractive index of the resin approaches that of the reinforcing filler particles (which remain constant throughout hardening) the amount of light scattering will decrease. The design of the OCT equipment in this proposal will measure the change in refractive index as the material hardens and will establish the relationship between refractive index change and volumetric shrinkage. The total amount of light scatter is also dependent on the size and shape of the filler particles and the absorption of chemical components within the resin responsible for hardening the material. Therefore, by testing RBCs with known composition (model formulations) a greater comprehension of the effect of refractive index change on hardening will provide a platform with which to improve the depth of cure and potentially the clinical durability of white-filling materials.This proposal aims to validate the use of a novel OCT technique to determine the change in optical properties of RBCs as they harden. Subsequently, the effect of material components (resin type and filler particle size and shape) on the change in refractive index in three-dimensions through the bulk of the RBC specimen can be established. This will facilitate a greater understanding of the setting characteristics, which ultimately has the potential to drive forward the development of light-activated RBCs.

大多数牙科患者更喜欢与他们天然牙齿的美学相匹配的填充材料。然而，大型“白色”填充物(树脂基复合材料；RBCs)的耐久性通常被认为不如非美观的“银质”填充物类型(牙科汞合金)。这可能与RBC固有的材料缺陷之外，对技术敏感的应用步骤的增加有关。现代RBC填充材料以糊状形式提供。它们由牙医直接在牙洞中模制，然后在高强度的蓝光下‘根据命令’设置为刚性材料。然而，RBC填充材料的固化深度有限(约2 mm)，因此牙医必须使用多个(增量)层来填充大型空洞，这与使用牙科汞齐不同，后者可以批量填充空洞，从而降低了技术敏感度、操作时间和成本。因此，提高固化深度的红细胞填充材料的开发是非常必要的，它可以改善此类材料的缺点，并最终提高其临床成功率，从而造福于患者社区。关于红细胞填充材料在高强度光下硬化时光学性质的变化，仍有许多悬而未决的问题，这可能为更好地了解固化反应，最终提高固化深度提供更多的洞察力。通过改变RBC的成分，包括填充了增强陶瓷颗粒的树脂基质，可以改变固化光透过材料的程度。这一独特的方案首次提供了使用光学相干层析成像(OCT)测量RBC材料硬化反应过程中光学性质变化的能力。随着RBC变硬，树脂成分变得更加致密并收缩。因此，树脂组分的折射率增加(改变通过材料的光速的特性)。随着树脂的折射率接近增强填料颗粒的折射率(在硬化过程中保持不变)，光散射的量将会减少。本方案中OCT设备的设计将测量材料变硬时折射率的变化，并建立折射率变化与体积收缩之间的关系。光散射的总量还取决于填料颗粒的大小和形状，以及树脂中负责硬化材料的化学成分的吸收。因此，通过测试已知成分的红细胞(模型配方)，更好地理解折射率变化对硬化的影响，将为提高白色填充材料的固化深度和潜在的临床耐久性提供一个平台。这项建议旨在验证使用一种新的OCT技术来确定红细胞硬化时光学性质的变化。随后，可以建立材料成分(树脂类型和填充颗粒的大小和形状)对通过RBC样品的整体在三维中的折射率变化的影响。这将有助于更好地了解环境特征，最终有可能推动光激活红细胞的发展。

项目成果

Real time optical and physical curing characteristics of dental resins

牙科树脂的实时光学和物理固化特性

• 发表时间: 2009
• 作者: Adrian Shortall