Dental radiographs are not mandatory for tooth decay, but they are recommended because they are very helpful in the diagnosis of tooth decay. The dental film can show the exact extent and depth of decay, whether the tooth is close to the pulp, whether there is apical hypodensity, and whether there is a significant widening of the periodontal membrane, which can guide the treatment of tooth decay. For early decay that is far from the pulp on dental radiographs, the decayed part of the tooth can be removed by simply applying the dental power system. The cavity is prepared with the resisting and retaining shape, and the filling material is applied to fill the cavity.