The main thing to look for in dental caries on dental films is the contrast in density, which is normally shown on dental films as a high density image for hard tissue and a low density image for soft tissue. First, the highest density relative to the entire dental film is enamel, which also shows the whitest high-density image. Second, dentin, is relatively less dense than enamel. Finally, the alveolar bone, being relatively loose, is the least dense of the high-density images, while for the soft tissues, the gums generally show a low-density image, while the air shows a distinctly black image. The most important thing to look for in caries is the low-density image in the high-density image, that is, the low-density shadow in the enamel and dentin corresponding to the site of caries, through which you can check the specific scope and depth of caries and whether it has invaded the pulp.