The inside of a tooth that has fallen out of a filling is black. The first thing you can do is to ask the patient about the time of the previous filling and the medical history, and ask if the patient knows what kind of filling material was used to repair the tooth. Because one of the traditional filling materials is silver amalgam, which is a black filling material after filling. At this time, we can apply the power system of dentistry to remove the original silver amalgam, prepare the cavity shape appropriately, and fill it with better filling material. However, if the amalgam was not applied before, most of the teeth fall out with black inside because of the secondary caries, that is to say, the caries appears again between the filling and the tooth, and the caries causes the change of color and texture of the hard tissue of the tooth. In this case, it is necessary to apply the turbine drill to further expand and remove the secondary caries and then perform 2 more repairs.