Transillumination of interproximal caries lesions with 830-nm light

New imaging technology is needed for the early detection of dental caries (decay) in the interproximal contact sites between teeth. Previous measurements have demonstrated that dental enamel is highly transparent in the near-IR near 1310-nm making that wavelength range ideal for the transillumination of interproximal lesions. However, imaging at 1310-nm involves the use of expensive InGaAs technology. The purpose of this study was to compare the performance of a low cost near-IR sensitive imaging system employing a CCD camera with enhanced near-IR sensitivity operating at 830-nm with the 1310-nm InGaAs system. Images of simulated caries lesions were acquired through tooth sections of varying thickness and whole teeth in order to demonstrate the utility of a near-IR dental transillumination system for the imaging of early dental caries (decay). Simulated lesions, representing the optical scattering of natural dental caries, were placed in plano-parallel dental enamel sections and whole anterior teeth. The contrast ratio between the simulated lesions and surrounding sound enamel was calculated from analysis of the respective spatial intensity profiles in the acquired projection images. This study shows that near-IR transillumination at 830-nm offers significantly improved image contrast over the visible range, but less image contrast than at 1310-nm.