Mechanical adaptation of cortical and trabecular bone morphology in the mammalian mandible

颌骨和牙齿的形态可以告诉我们很多关于动物如何分解食物的信息。例如，牛和羊等食草动物具有相对平顶的牙齿和颌骨关节，允许下颌水平运动，以便研磨食物。另一方面，食肉动物如猫，有刀片状的牙齿和下颌关节，只允许下颌垂直运动。这些分解食物的不同方式导致作用在牙齿和颌骨上的力非常不同，这就提出了几个基本问题：咀嚼力是如何从牙齿通过颌骨传递的？牙齿形状在这些力的分布中起什么作用？颌骨如何适应这些不同的力量？然而，回答这些问题并不是一件容易的事，因为目前缺少重要的信息。首先，很少有人知道哺乳动物物种之间的颌骨的内部形态（几何形状）的变化，因为这种形态的全面研究取决于高分辨率计算机断层扫描的可用性，这些已经成为最近才可用。其次，由不同的咀嚼力引起的骨骼中的应变并不为人所知，并且只能在骨骼表面上测量。我们将通过研究具有非常不同和众所周知的进食适应性的哺乳动物物种的下颌内部形态来解决这些问题。我们将应用基于高分辨率数据的最先进的图像处理，功能计算机建模和机械实验的组合。我们将集中在下颌的一部分，这是众所周知的经历高应力和应变在咀嚼，骨下的脸颊牙齿。总体目标是了解内部骨形态，牙齿形态和咀嚼力之间的联系。我们的团队和密切的合作者在咀嚼功能的建模和颅骨机械适应的研究方面有着非常强的研究记录。我们已经为哺乳动物（包括人类在内的灵长类动物）和爬行动物（蜥蜴）的头骨的形式和功能提供了新的见解，并在此过程中为这类工作开发了新的方法。此外，我们已经研究了现代人类和尼安德特人下颌骨不同形状的机械意义。拟议的项目将继续和联合收割机这些成功的研究线，以阐明咀嚼负荷和非常不同的饮食习惯的哺乳动物物种的下颌骨的内部和外部结构之间的关系。有了这些重要的基础知识，我们计划在随后的建议中扩展这项工作，以考虑临床和牙科应用，特别是咀嚼器官的老化，牙齿脱落和直接附着在骨骼上的最新一代牙科植入物的替代。我们的工作将有许多受益者，包括来自不同学科的研究人员（例如，比较解剖学，功能形态学，古生物学，牙科学），英国科学基础（通过跨学科框架中的年轻科学家培训，吸引海外学生和合作者），更广泛的公众（公众参与，媒体兴趣）和临床医生（牙医和牙医）。

The morphology of jaws and teeth can tell us much about how an animal breaks down its food. Herbivorous animals such as cows and sheep have, for example, relatively flat-topped teeth and jaw joints that allow horizontal movements of the lower jaw so that they can grind their food. Meat-eating animals such as cats, on the other hand, have blade-like teeth and jaw joints that allow only vertical movements of the lower jaw. These different ways of breaking down food cause very different forces acting on the teeth and jaw bones, which raise several fundamental questions: How are chewing forces transferred from the teeth through the jaws? What role does tooth shape play in the distribution of these forces? How does the bone in the jaws adapt to these different forces? However, answering these questions is not an easy task, since important information is currently missing. Firstly, little is known about the variation of the internal morphology (geometry) of the jaws between mammalian species, since a comprehensive study of this morphology depends on the availability of high-resolution computed tomography scans and these have become available only recently. Secondly, the strains in the bone resulting from different chewing forces are not well known, and can only be measured on the bone surface. We will address these questions by studying the internal morphology of the lower jaw in mammal species with very different and well-known feeding adaptations. We will apply a combination of state-of-the-art image processing based on high-resolution data, functional computer modelling and mechanical experiments. We will focus on a part of the lower jaw that is known to experience high stresses and strains during chewing, the bone beneath the cheek teeth. The overarching aim is to understand the link between internal bone morphology, tooth morphology and chewing forces. Our group and close collaborators have a very strong research record in the modelling of masticatory function and the study of mechanical adaptations in the skull. We have already provided new insights into the form and function of the skull in mammals (primates including humans) and reptiles (lizards), and in the process developed new methodological approaches for this type of work. Plus we have already examined the mechanical significance of the different shapes of modern human and Neanderthal mandibles. The proposed project will continue and combine these successful lines of research to elucidate the relationships between masticatory loads and the internal and external architecture of the mandible in mammal species with very different dietary habits. With this vital underpinning knowledge, we then plan to extend this work in subsequent proposals to consider clinical and dental applications, especially ageing of the masticatory apparatus, tooth loss and replacement by the latest generation of dental implants which attach directly to the bone. There will be many beneficiaries of our work, including researchers from diverse disciplines (such as, comparative anatomy, functional morphology, palaeontology, dentistry), the UK science base in general (through training of young scientists in an interdisciplinary framework, attraction of overseas students and collaborators), the wider public (public engagement, media interest) and clinicians (dentists and orthodontists).