OVERVIEW

It will be recalled from the last chapter just how dependent the rate of food breakdown is on tooth size. However, the exposed surfaces of the teeth are subject to wear, either from food, grit or opposing tooth surfaces. Wear threatens to destroy tooth shape, decreasing the rate of food breakdown and so jeopardizing a mammal's health. Insofar as the food input is responsible for this wear, the rate must depend on the characteristics of the food surface, i.e. on the external physical attributes of foods, because wear involves small-scale events involving the interaction of surfaces. Maintaining the argument from Chapter 1, I expect the evolved response to this threat to lie in adaptation of tooth size. This chapter follows through the logic of this argument and also tries to identify the major causes of tooth wear.

INTRODUCTION

Wear is the loss of volume of an object and results from a number of processes rather than just being one process in itself. It may often involve fracture, but the chemical dissolution of stony objects like teeth also comes under the same general heading. Teeth wear mostly on their working surfaces, but any other tooth surface exposed to the oral cavity can wear too. Movement of food by the tongue and cheeks against the teeth is sufficient to cause a small amount of wear (Fox et al.