Tooth decay on teeth should be filled promptly because it is a progressive destruction by bacteria that does not heal itself and can only be repaired after the decay has been removed. The repair is done by removing the decay with a dental drill and bonding it to the tooth surface with a replacement material, usually glass ionomer or light-curing composite resin. If it is close to the nerve, calcium hydroxide material can be used and then the tooth can be filled with indirect pulp capping. If the nerve is already exposed, pain will occur, then it is necessary to kill the nerve treatment, after killing the nerve, you can do the tooth dry pulp surgery, also can do the tooth root canal treatment, root canal treatment is to remove the nerve, the treatment effect is more thorough, usually after the treatment, you need to do the crown restoration to prevent the tooth fracture. Usually, if there is a cavity on the tooth, it should be repaired as soon as it is found to avoid the cavity getting bigger and bigger.