Agrawal Kalpana R, Lucas Peter W
Department of Anatomy, University of Hong Kong, 21 Sassoon Road, Hong Kong SAR, PR China.
Proc Biol Sci. 2003 Jun 22;270(1521):1277-82. doi: 10.1098/rspb.2003.2361.
An analysis of the action of the incisor teeth in humans is presented in terms of the fracture of food particles. It is predicted that the resistance of foods with an essentially linear elastic response to an initial bite by the incisors will depend on the square root of the product of two food properties, Young's modulus and toughness. This quantity should be approximately equal to the product of the stress at cracking during a bite, and the square root of the length of a notch or indentation from which that crack initiates. As a test of the theory, the relationship between in vivo stresses and the depth of incisal penetration, measured during bites on seven 'snack' foods by 10 subjects, and food properties established from mechanical testing, was investigated. Theory and experiment were found to be in excellent agreement. A dimensionless index of the efficiency of incision is suggested, relating fracture performance by subjects to values from a testing machine. This appears to have a high level of inter-subject discrimination with efficiencies varying about threefold. The method appears to have potential applications in dentistry, food science and studies of human and primate evolution.
本文从食物颗粒的断裂角度对人类门牙的作用进行了分析。据预测，对门牙初次咬合呈现基本线性弹性响应的食物，其抗力将取决于两种食物特性（杨氏模量和韧性）乘积的平方根。该量应大致等于咬合过程中开裂时的应力与裂纹起始处缺口或压痕长度的平方根的乘积。作为对该理论的检验，研究了10名受试者在咬七种“零食”食物时所测量的体内应力与切牙穿透深度之间的关系，以及通过机械测试确定的食物特性。结果发现理论与实验吻合度极高。提出了一个无量纲的切割效率指数，将受试者的断裂性能与试验机的值联系起来。这似乎具有较高的受试者间区分度，效率变化约为三倍。该方法似乎在牙科、食品科学以及人类和灵长类动物进化研究中具有潜在应用。
