Timothy G. Bromagea
Figure 1: Human enamel microanatomical structure. In this example of modern human enamel deep to the surface of a transversely cut and polished tooth and imaged by backscattered electron imaging in the scanning electron microscope, we see that the prisms have divergent courses. Some prisms are seen to course longitudinally and wander lengthwise in the plane of the image while others course in and out of the plane of the image and appear semicircular. This heterogeneity provides crack propagating resistance to a tooth, enabling it to withstand the mechanical forces of chewing. Color was imparted to the image by an image analysis program for measuring prism orientation. Field width 180 µm.