VARIATIONS IN THE MECHANICAL, CHEMICAL, AND MICROSTRUCTURAL PROPERTIES OF ENAMEL

Teeth are important in the survival of humans and animals and have functions in mastication, esthetics, speech, and protection. Teeth are composed of a hard outer covering of enamel, a mid-layer of softer dentin, and an inner layer of pulp. The various layers of teeth can be considered different materials and have different functions, structures, and properties. In this research, the focus is on the outer layer of tooth structure. Enamel is a complex composite consisting of hydroxyapatite, water and organic material. Enamel is highly mineralized and forms anisotropic prisms which are supported underneath by the less mineralized dentin. It was historically assumed that each of the layers of tooth structure were homogeneous materials with consistent properties throughout. However, studies have revealed that this is not the case. This research characterizes variations in the mechanical properties, microstructure, and chemistry of enamel at different locations in the tooth and in different tooth types, and it determines the source of the variations in mechanical properties. In addition, the results of experimental testing of the mechanical properties are used to develop a model of tooth deformation during mastication. In addition, variations found in the mechanical properties, microstructure, and chemistry of human enamel are compared to another species with a different diet and from a different environment. Increased knowledge of enamel and its properties could provide insight into tooth wear, development of dental restorative materials, and preparation of teeth for restorations