Patient: caries, food filling started in cavity two months ago, sensitivity to hot and cold stimuli. Laboratory tests and radiographs of the cavity on the side, closer to the pulp. The first time, on August 8, 2008, the endodontist killed the nerve; the second time, on August 23, 2008, the emergency department doctor root canal treatment: extraction of pulp, root canal reaming, laser measured the depth of the root canal, root canal (preparation), “preparation” do not know what it means? I don’t know what “preparation” means, but I was told that it was filled with some antiseptic. I felt that the treatment was average, the filling was not adequate, and I had to eat and fill with food. What will be the content of the third treatment, can I change the doctor, can I change your number? Ling Jianjun, Endodontics, Beijing Stomatological Hospital: How many root canal treatments are needed? This is a very specialized question, which is generally directly related to the condition, technical requirements, external environment, etc. It is usually said that root canal treatment requires one to three times to complete. The classic root canal treatment is usually divided into three steps: 1) applying a nerve-killing agent; 2) removing the nerve, unblocking, cleaning, preparing and sterilizing the root canal; and 3) filling the root canal and, if appropriate, the surface. The patient has every right to choose his or her doctor, but generally speaking, as a doctor the second step of root canal treatment is not exactly the same in terms of requirements and standards, so picking up the last step halfway through the process may cause some inconvenience to your treatment. If I don’t go out for a meeting, my clinic time is usually very fixed. Recently, it is not so good for endodontics, so if you want to register with our department, you’d better arrive before 7:30, or even earlier. If you want to see me, you should say hello to the triage nurse at the front desk in advance, so that you can schedule your appointment as early as possible, because your treatment will be divided into at least two steps on the same day, and in the middle, you will need to take X-rays to make sure that the root fillings are good or bad. May you have a good dental experience and mood!