Generally speaking, rectal cancer surgery is not directly related to tooth loss, but may be related to chemotherapy or radiotherapy and other reasons. 1. Chemotherapy: chemotherapy is the most commonly used treatment for cancer, generally after chemotherapy, patients may lose teeth, and most of them may have hair loss or fever. Chemotherapy can control the growth of cancer cells in time and prolong the life of patients, so they should actively cooperate with doctors, and communicate with doctors in time if they have any problems. 2. Radiotherapy: Radiotherapy, as a technique of studying radioactive substances or treating tumors with radiotherapy, is often used in the treatment of patients with various malignant tumors. Although radiotherapy is a kind of local treatment method, while killing tumor cells, it will also have certain damage to human body, and may cause tooth loss, hair loss, nausea, vomiting and other adverse symptoms. 3. Others: diseases of teeth itself, such as dental caries, root lesions and so on. If the above symptoms appear after rectal cancer surgery, it is recommended to go to the hospital for checkup and communicate more with doctors for clear diagnosis.