PS-OCT of occlusal and interproximal caries lesions viewed from occlusal surfaces

Previous studies have demonstrated that Polarization Sensitive Optical Coherence Tomography (PS-OCT) can be used to image early dental caries. The primary objective of this study was to compare the measured reflectivity of natural occlusal caries lesions with the relative mineral loss measured using digital microradiography. There was excellent agreement between the increase in the integrated reflectivity in the perpendicular polarization axis of the PS-OCT system and the increase in the integrated mineral loss or lesion severity for occlusal lesions. Therefore, PS-OCT is ideally suited to image natural caries lesions in the important occlusal surfaces for the assessment of the lesion severity and activity. A secondary objective was to compare the performance of a new autocorrelator-based PS-OCT system employing a novel polarization-switching probe with our polarization-maintaining fiber based PS-OCT system, both operating at 1310-nm. The new PS-OCT system produced clean images with no artifacts and achieved high penetration depth. Yet a third objective was to determine if interproximal lesions can be imaged from the occlusal surface (from above) since interproximal lesions may only be accessible in vivo from buccal or lingual surfaces or from the occlusal surface. Simulated and natural interproximal caries lesions were imaged from the occlusal surfaces as long as there was no intervening dentin.