Elucidating the pathways for human tooth enamel mineralisation by 4D microscopy and microfluidics

牙釉质是身体中最坚硬的矿化组织，其复杂的分层微结构允许不同的结构适应口腔中的强大挑战。然而，与其他组织不同，釉质缺乏修复或重塑的能力，并且在由粘附于牙齿结构的细菌产生的酸的攻击条件下，它失去其完整性并引发龋齿（最普遍的牙科疾病）的进展。尽管通过氟化改善口腔卫生和预防措施做出了巨大努力，但仍有超过23亿成年人患有龋齿（2017年全球疾病负担），每年的巨额支出高达34亿英镑（英国公共卫生2020年，英国NHS 2014年）。国家报告中提出的这些令人不安的细节强调了这一研究课题的首要意义及其对国民经济、科学界和整个社会的重大影响。为了解决这个问题，现代牙科现在的目标是通过在龋齿发展的初始/初期阶段促进釉质修复来遏制这种牙科疾病，以防止在后期阶段需要侵入性修复程序。在这项研究提案中，我们希望通过研究不同长度尺度（纳米到微米到宏观）的釉质结构的分级组装来解决早期釉质龋，并基于这种理解，开发和完善修复/再矿化的新策略，并最终获得直接在患者口中再生具有最佳结构和改善性能的釉质的能力。通过采用伯明翰牙科研究专家和牛津多模态显微镜，光谱学和建模专家的联合跨学科方法，我们打算通过将传统牙科技术（如临床可视化，触觉感知，放射摄影，实验室计算机断层扫描等）与时间分辨3D结构（因此4D）评估相结合来分析釉质脱矿和修复。这将通过先进的显微成像和光谱技术与微流体技术相结合，在从原子晶格到纳米、微米和宏观尺度的空间分辨率下完成。提议者与世界各地不同大学、公司和执业牙医的研究小组有联系。与GlaxoSmithKline的工业合作伙伴关系以及与Diamond Light Source的长期合作关系（英国同步加速器）、ISIS中子和μ子源、Tescan和牛津仪器将提供最先进的研究方法，并确保产生最广泛的国家和国际影响。项目目标包括：（i）确定和确保代表性样品的供应，（ii）观察早期龋齿脱矿过程中釉质的超微结构演变，（iii）开发和改进微创脱矿程序，以及（iv）开发多尺度数学模型。该工作计划涵盖了EPSRC医疗保健技术大挑战的所有主题，从开发未来疗法和物理干预前沿到优化治疗和转变社区卫生和护理。此外，宏观和微观流体系统，微生物学策略，多模态显微镜，釉质结构和完整疾病过程的数学建模的发展将有助于先进材料，新型成像技术和新型计算和数学科学领域的跨领域研究能力的进步。该项目成功的最大预期结果将是引入新的侵入性最小的逆转或预防釉质龋的方法，这将对个人和经济以及整个社会产生巨大的益处。

Dental enamel is the hardest mineralised tissue in the body and its complex hierarchical microstructure allows different structural adaptations against the robust challenges in the oral cavity. However, unlike other tissues, enamel lacks the ability to repair or remodel and under conditions of attack by acid produced from bacteria adhering to tooth structure, it loses its integrity and initiates the progression of dental caries, the most widespread dental disease. Despite tremendous efforts to improve oral hygiene and preventive measures by means of fluoridation, more than 2.3 billion adults suffer from caries (Global burden of Disease 2017) and account for massive expenditure as high as £3.4 billion every year (Public health England 2020, NHS England 2014). These distressing details presented in national reports emphasize the prime importance of this research topic and its significant impact on national economy, scientific community, and society in general. To tackle the problem, modern dentistry now aims to curb this dental disease by promoting enamel repair at the initial/incipient stages of caries development to prevent the need for invasive restorative procedures at later stages. In this research proposal we wish to tackle incipient enamel caries by investigating the hierarchical assembly of enamel structure at different length scales (nano- to micro- to macro-) and based on this understanding, develop and refine a new strategy for repair/remineralisation, and ultimately obtain the ability to regenerate enamel with optimal structure and improved properties directly in patients' mouths. By employing a joint interdisciplinary approach involving specialists in dental research at Birmingham and specialists in multimodal microscopy, spectroscopy and modelling at Oxford, we intend to analyse the enamel demineralisation as well as repair by combining conventional dentistry techniques such as clinical visualisation, tactile perception, radiography, laboratory computed tomography etc. with time-resolved 3D structural (hence 4D) evaluation. This will be done at the spatial resolution ranging from atomic crystal lattice to nano, micro-, and macro-scale by advanced microscopic imaging and spectroscopic techniques integrated with microfluidics.The proposers have worldwide associations with research groups across different universities, companies and practicing dentists. Industrial partnership with GlaxoSmithKline and the long established collaborative link with Diamond Light Source (UK synchrotron), ISIS Neutron and Muon source, Tescan and Oxford instruments will provide access to state-of-the-art research methodologies and ensure delivering broadest national and international impact.The project objectives cover (i) identifying and securing supply of representative samples, (ii) observing ultrastructural evolution of enamel during incipient caries demineralisation, (iii) developing and refining minimally invasive remineralisation procedures, and (iv) developing multi-scale mathematical models. This work plan encompasses all themes of EPSRC Healthcare Technologies Grand Challenges ranging from developing future therapies and frontiers of physical intervention to optimising treatment and transforming community health and care. Additionally, the development of macro- and micro-fluidic systems, remineralisation strategies, multi-modal microscopy, and mathematical modelling of enamel structure and the complete disease process shall contribute to the advancement of Cross-Cutting Research Capabilities in areas of advanced materials, novel imaging technologies, and novel computational and mathematical sciences, respectively.The greatest anticipated outcome from the success of this project will be the introduction of new minimally intrusive means of reversing or preventing enamel caries that will be of massive benefit to individuals and the economy, and the society at large.