Root canal treatment is not always necessary for fillings. Whether or not root canal treatment is needed depends on whether or not the degree of decay of the tooth is very serious. If there is only a relatively small cavity on the surface of the tooth, the tooth usually have no pain, this stage of the tooth just need to do a resin material filling will be able to fill the tooth, do not need to do root canal treatment. If the tooth is more seriously decayed, has injured the root canal of the pulp, and even developed into pulpitis, then need to do root canal treatment. Root canal treatment involves removing all the inflamed and infected material from the root canals, then disinfecting and disinfecting them, and finally filling the cavities. A radiograph of the oral cavity can be taken to check the extent of decay and whether the pulp and nerve are infected to determine whether root canal treatment is necessary.