Published online by Cambridge University Press: 04 August 2010
Virtually the entire dental literature deals with the function of teeth from a geometrical perspective. In this chapter, the first of three forming the core of this book, I advance the alternative hypothesis that the mechanical behaviour of foods is the major influence on tooth shape. The principal mechanical properties of foods involved are the Young's modulus and toughness. However, I will also be referring to more specific influences such as the level of stresses within foods, the yield strength, strain and Poisson's ratio. To understand these concepts clearly, the reader is advised to work through Appendix A before reading further. While some of the influences on tooth shape can be quantified fairly precisely, others are too complex for this. The analysis then has to borrow from simpler circumstances in which the basic principles have been established. The chapter starts by assuming that foods are homogeneous solids, but the value of understanding features of food structure such as their internal connectivity should quickly become apparent. To keep things simple, all through the chapter, the basic analysis assumes linear elastic behaviour in foods. Only general principles of dental–dietary adaptation are emphasized because Chapter 7 deals with real dentitions.
The toughness of foods plays a crucial role in shaping teeth. Unfortunately, toughness is an energetic concept that still seems alien to most biologists.