Tooth decay is also called caries, if the caries area is small, the depth does not reach the nerve can be removed after the decayed tissue with resin filling, restore the shape of the tooth, the tooth can also continue to exercise chewing function, restore aesthetic. If the bacteria have already eroded to the nerve, root canal treatment is needed to remove the nerve completely, and then fill the root canal with hot cement, and finally make inlays or crowns on top of it to restore the shape of the tooth as well as its chewing function. If the patient does not consult the doctor in time, let the tooth continue to decay is likely to hurt the root of the tooth, then the tooth basically can not be retained, need to be extracted as soon as possible, and then later implant restoration.