If the tooth still has significant pain after the root canal treatment, there are two reasons to consider: the first reason is the doctor’s misdiagnosis of the disease before the operation. If the patient suffers from jaw bone cyst or jaw bone tumor, the painful discomfort will still occur if the tumor and cyst are not removed after the root canal treatment of the tooth alone. A full-mouth surface tomogram must be taken to determine the location of the tumor cyst, and the tooth pain will disappear completely after the surgical removal procedure. The second reason could be that the doctor was defective in performing the root canal treatment, such as underfilling or overfilling, either underfilling or overfilling, which will still cause the tooth to be painful later and require a complete root canal treatment of the tooth again.