There are several cases of blackened tooth roots as follows: 1, there is no big problem on the tooth surface itself, no caries, no inflammation, but the direction of the tooth root is blackened, it can be considered that the tartar accumulation under the gums, the gums may be in a congested, edematous state, this situation will appear when brushing teeth or gnawing apples, gnawing bones, gum bleeding; 2, the teeth have been traumatized before, the teeth slowly become black, after the trauma inside the tiny Capillary rupture, red blood cells free into the dentin tubules lead to black teeth; 3, many people did porcelain crowns, porcelain bridges, root party, if the root of the tooth black, suggesting that may be the former porcelain inside the free metal ions, erosion to the root party led to the root of the black. The above three situations are more common in the clinic.