The main reason for tooth discoloration due to pulp necrosis is that the pulp consists of blood vessels and nerves, and when the pulp is necrotic, the nerves and red blood cells are also necrotic, and the hemoglobin decomposition in the red blood cells will adhere to the crown of the tooth, causing the color of the crown to change. Therefore, the color of the tooth becomes darker after pulp necrosis, especially in the front teeth, and it also affects the aesthetics. In the case of pulpal necrosis, patients are reminded to go to the hospital for root canal treatment and then crown restoration to restore the normal color of the tooth. After pulpal necrosis is restored with a crown, the tooth will be durable for a long time. If left untreated, a tooth with necrotic pulp will eventually lead to apical lesions, tooth splitting, and ultimately, irretrievable extraction.