New imaging technologies are 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 at 1300-nm. In this study, a near-IR imaging system operating at 1300-nm was used to acquire images 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, which model the optical scattering of natural dental caries, were placed in piano-parallel dental enamel sections. The contrast ratio between the simulated lesions and surrounding sound enamel was calculated from analysis of acquired projection images. The results show significant contrast between the lesion and the enamel (>0.35) and a spatial line profile that clearly resolves the lesion in samples as thick as 6.75-mm. This study clearly demonstrates that a near-IR transillumination system has considerable potential for the imaging of early dental decay.