The teeth that require root canal treatment are often inflamed because of the pulp. During root canal treatment, the doctor will remove the infected tissue in the root canal and then fill the canal with sterile dental cement and other root canal filling materials to ensure that there is no dead space in the root canal to avoid future inflammation. After the root canal treatment, the tooth tissue will become brittle due to the lack of pulp nutrition, so the doctor usually requires the use of piles to enhance the fracture resistance of the tooth. Therefore, it is generally recommended to observe the tooth for about a week after root canal treatment to ensure that the tooth does not become painful before starting to make piles and crowns. When the apical infection is severe, sometimes the observation period can be longer.