Ultrasonic assessment of tooth structure

A means of assessing the internal structure of teeth based upon use of high frequency, highly localized ultrasound (acoustic waves) generated by a short laser pulse is discussed. Some key advantages of laser-generated ultrasound over more traditional contact transducer methods are that it is noncontact and nondestructive in nature and requires no special surface preparation. Optical interferometric detection of ultrasound provides a complementary nondestructive, noncontact technique with a very small detection footprint. This combination of techniques, termed laser-based ultrasonics, holds promise for future in-vivo diagnostics of tooth health. In this paper, initial results using laser-based ultrasound for assessment of dental structures are presented on an extracted human incisor. Results show the technique to be sensitive to the enamel/dentin, dentin/pulp, and dentin/cementum junctions as well as a region of dead tracts in the dentin.