Polarization-sensitive optical coherence tomography of dental structures

Optical coherence tomography (OCT) has been developed during the last 10 years as a new noninvasive imaging tool and has been applied to diagnose different ocular and skin diseases. This technique has been modified for cross-sectional imaging of dental structures. In this first preliminary study the technique was applied to obtain tomographic images of extracted sound and decayed human teeth in order to evaluate its possible diagnostic potential for dental applications. Classical OCT images based on reflectivity measurements and phase retardation images using polarization-sensitive OCT were recorded. It was demonstrated that polarization-sensitive OCT can provide additional information which is probably related to the mineralization status and/or the scattering properties of the dental material. One of the attractive features of OCT is that it uses near-infrared light instead of ionizing radiation. Furthermore, high transversal and depth resolution on the order of 10 microm can be obtained. Present limitations, e.g. the limited penetration depth, and possible solutions are discussed.