The Caries Lesion Under the Scanning Acoustic Microscope

Abstract

The scanning acoustic microscope can be used to obtain images of caries lesions in longitudinal sections of human enamel. The contrast in the acoustic images is unique in that it arises from changes in the elastic properties across the surface of a specimen. The contrast depends sensitively on the distance between the specimen and the focal plane of the lens, and this can be exploited to reveal features of interest. Comparison of an acoustic micrograph, a polarized light micrograph, and a microradiograph of a caries lesion reveals that the elastic properties of enamel are strongly dependent on the level of mineralization within the tissue. Acoustic micrographs show regions similar to those seen with the other techniques, but with greater sensitivity to small changes in mineralization.