The popular term for tooth decay is also known as dental caries. Depending on the depth of caries, a resin filling or a filling after root canal treatment will be used. 1. Resin filling: If the cavity has not progressed to the pulp, it is necessary to use special instruments to grind away the decayed tooth tissue and then use resin filling to restore the normal shape of the tooth and prevent the caries from deepening. 2. Filling after root canal treatment: If the caries has progressed to the pulp, root canal treatment is needed to remove the infected pulp tissue before resin filling, and then consider crown restoration to protect the tooth tissue. It is recommended to go to the hospital in time to avoid deepening of caries and inflammation, and at the same time, regular oral examination is needed to find problems in time.