Dental radiographs view the extent of dental caries, mainly to see the extent of caries invasion, as well as how far the caries are from the pulp and how far they have invaded the pulp. Generally in dental films, the hard tissue shows a high density image, where the highest density is the enamel, which is the hardest part of the body, the rest of the dentin is relatively low density, and the alveolar bone is a low density image in a relatively high density shadow. And for the low-density image, black is the lowest density image, generally shows the air, the rest can show to the low-density image refers to the soft tissue. At this point it is necessary to view the site of specific caries, caries are in the enamel and dentin on the low-density low-density image, to view the specific extent of caries and caries distance from the pulp, you can view the extent of caries.