Imaging of occlusal dental caries (decay) with near-IR light at 1310-nm

Dental enamel manifests high transparency in the near-IR. Previous work demonstrated that near-IR light at 1310-nm is ideally suited for the transillumination of interproximal dental caries ( dental decay in between teeth) [ 1]. However, most new dental decay occurs in the pits and fissures of the occlusal ( biting) surfaces of posterior teeth. These caries lesions cannot be detected by x-rays during the early stages of decay due to the overlapping topography of the crown of the tooth. In this study, a near-IR imaging system operating at 1310-nm was used to acquire occlusal images by launching the near-IR light into the buccal surface of the tooth just above the gingival margin (gum-line). The near-IR light diffuses through the highly scattering dentin providing uniform back illumination of the enamel of the crowns allowing imaging of the occlusal surfaces. The near- IR images show high contrast between sound and demineralized areas. Demineralization ( decay) can be easily differentiated from stains, pigmentation, and hypomineralization ( fluorosis). Moreover, the high transparency of the enamel enables imaging at greater depth for the detection of subsurface decay hidden under the enamel. These early images suggest that the near- IR offers significant advantages over conventional visual, tactile and radiographic caries detection methods. (C) 2005 Optical Society of America.