Interactions Between Oral Biofilms and Dental Resin Composites

口腔生物膜和牙科树脂复合材料之间的相互作用

• 批准号: 8304161
• 负责人: Alex Siu-Lun Fok
• 金额: $ 37.37万
• 依托单位: UNIVERSITY OF MINNESOTA
• 依托单位国家: 美国
• 财政年份: 2010
• 资助国家: 美国
• 起止时间: 2010-09-10 至 2014-08-31
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/8304161
• 关键词: Accounting; Address; Anti-Bacterial Agents; Biological Models; Clinical; Clinical Research; Composite Dental Resin; Composite Resins; Dental; Dental Enamel; Dental caries; Dentists; Dentition; Development; Diagnosis; Failure; Fourier transform infrared spectrometry; Future; Goals; Growth; Health Care Costs; Human; Image; Individual; Knowledge; Laboratory Study; Life; Mechanics; Metabolism; Methods; Microbe; Microbial Biofilms; Minerals; Minnesota; Modeling; Monitor; Optics; Oral; Oral cavity; Patients; Property; Recurrence; Saliva; Sampling; Services; Sterility; Stress; System; Testing; Time; Tooth Tissue; Tooth structure; Virulence; X-Ray Computed Tomography; base; composite restoration; dental resin; design; improved; in vitro Model; next generation; oral biofilm; public health relevance; restoration; restorative dentistry; sound

DESCRIPTION (provided by applicant): The long-term goal of this project is to increase the service life of dental resin composite restorations by obtaining a fundamental understanding of the development of secondary caries. Our more immediate goal is to test the hypothesis that oral biofilms contribute to the degradation of the margin, leading to more frequent instances of secondary caries. That might occur because composite materials select for a more cariogenic flora at the margin, or because products of bacterial metabolism contribute to the breakdown of the composite itself. Neither mechanism is mutually exclusive, so each question will be addressed in complementary clinical and laboratory studies, as described in the Specific Aims: 1.) Compare the bacterial species composition of biofilms collected from the enamel interface of sound amalgam restorations, sound composite restorations, composites with early secondary caries, and composites with frank secondary caries. Human Oral Microbe Identification Microarrays will be used to provide biofilm profiles incorporating 272 species. We will be testing the hypothesis that composite-enamel interfaces are colonized by distinctive bacterial species, compared to amalgam-enamel interfaces. Such ecological selection could account for an increase in virulence of the biofilm at the tooth-composite interface. Near-infrared optical computed tomography (OCT) will be used as an important adjunct to our clinical caries diagnosis, by detecting caries earlier than conventional methods, and confirming sound interfaces. 2.) Bridge our clinical and laboratory studies by optimizing a biofilm reactor system for growing multi-species oral biofilm microcosms at the composite-enamel interface of restorations placed in extracted teeth and coated with saliva. This system will provide the basis for testing the hypothesis that products of bacterial metabolism contribute to composite breakdown. Plaque samples from the clinical study will be used to establish microcosms corresponding to composite-enamel interfaces with no caries, early caries, or frank caries. The HOMIM system will be used to monitor the species composition of microcosms, and determine the conditions needed to reproduce the major species profiles of biofilms from patient samples. 3.) Use the Minnesota Artificial Mouth to incorporate load cycling into the biofilm reactor model. Composite restorations placed in extracted teeth will be subjected to repeated cycles of saliva coating, biofilm growth in the reactor, and loading in the artificial mouth. Teeth restored with composites that generate different levels of shrinkage stress will be exposed to the different types of microcosm, and also to sterile saliva medium alone, with or without loading. Both OCT and micro-CT imaging will be used to monitor the loss of minerals in the tooth tissues, while microhardness testing and Fourier-transform infrared spectrometry will be performed to assess changes in the composites. This in vitro model system will be used to test the hypothesis that defined bacterial microcosms and mechanical loading exert individual and combined effects on the material properties of composite restorations, degradation of the tooth-restoration margin and the time to restoration failure. PUBLIC HEALTH RELEVANCE: Replacing failed dental restorations takes up 70% of a dentist's effort and contributes $5 billion to health care costs in the US. Among the different types of restorations, composite restorations have been shown to have a higher failure rate than amalgam restorations, with the main cause of failure being secondary or recurrent caries. The knowledge gained from this and future projects will help guide the design of the next generation of dental composite materials, which are likely to require reduced shrinkage stress, improved bond strengths, as well as antibacterial and cariostatic capabilities.

描述（由申请人提供）：该项目的长期目标是通过获得对继发龋发展的基本了解来延长牙科树脂复合修复体的使用寿命。我们更直接的目标是检验口腔生物膜导致边缘退化的假设，从而导致更频繁的继发龋病例。发生这种情况的原因可能是复合材料在边缘选择了更多致龋菌群，或者因为细菌代谢产物导致了复合材料本身的分解。这两种机制都不是相互排斥的，因此每个问题都将在互补的临床和实验室研究中得到解决，如具体目标中所述：1.) 比较从健全的汞合金修复体、健全的复合修复体的牙釉质界面收集的生物膜的细菌种类组成，具有早期继发龋的复合材料和具有明显继发龋的复合材料。人类口腔微生物识别微阵列将用于提供包含 272 个物种的生物膜图谱。我们将测试以下假设：与汞齐牙釉质界面相比，复合牙釉质界面被独特的细菌物种定植。这种生态选择可以解释牙齿-复合材料界面处生物膜毒力的增加。近红外光学计算机断层扫描（OCT）将作为临床龋齿诊断的重要辅助手段，比传统方法更早地检测出龋齿并确认良好的界面。 2.) 通过优化生物膜反应器系统来连接我们的临床和实验室研究，该系统用于在放置在拔除的牙齿中并涂有唾液的修复体的复合牙釉质界面上生长多物种口腔生物膜微观世界。该系统将为检验细菌代谢产物有助于复合材料分解的假设提供基础。临床研究中的牙菌斑样本将用于建立与无龋齿、早期龋齿或明显龋齿的复合牙釉质界面相对应的微观世界。 HOMIM 系统将用于监测微观世界的物种组成，并确定从患者样本中重现生物膜主要物种特征所需的条件。 3.) 使用明尼苏达人工嘴将负载循环纳入生物膜反应器模型中。放置在拔出的牙齿中的复合修复体将经历唾液涂层、反应器中生物膜生长以及人工口腔中装载的重复循环。使用产生不同水平收缩应力的复合材料修复的牙齿将暴露于不同类型的微观世界，并且还暴露于单独的无菌唾液介质，有或没有负载。 OCT 和显微 CT 成像将用于监测牙齿组织中矿物质的损失，同时将进行显微硬度测试和傅里叶变换红外光谱测量以评估复合材料的变化。该体外模型系统将用于测试以下假设：定义的细菌微观世界和机械载荷对复合修复体的材料特性、牙齿修复体边缘的退化和修复体失败的时间产生单独和组合的影响。 公共健康相关性：更换失败的牙齿修复体需要牙医 70% 的努力，并为美国医疗保健费用贡献 50 亿美元。在不同类型的修复体中，复合修复体的失败率高于汞合金修复体，失败的主要原因是继发性或复发性龋齿。从这个项目和未来的项目中获得的知识将有助于指导下一代牙科复合材料的设计，这些材料可能需要降低收缩应力、提高粘合强度以及抗菌和防龋能力。