Once a patient decides to undergo orthodontic treatment, the doctor has to conduct a detailed examination of the patient in order to fully understand the patient’s problems and then formulate a treatment plan. The examination is divided into two parts, one is clinical examination; the second is auxiliary examination. Clinical examination 1, communicate with the patient to understand the patient’s general condition and oral local conditions and requirements for orthodontic treatment. 2.To further check the patient’s condition especially the oral and maxillofacial condition by looking, touching and looking. Auxiliary examination Auxiliary examination is essential in the clinic, because we need a lot of information that the clinical examination can not provide, and there are many other aspects that we can not see with the naked eye, such as the situation of the bone, the root of the tooth, etc., then auxiliary examination must be used. So what are the auxiliary tests? 1, the model of each patient we have to make a model. There are several models for orthodontic patients. Preoperative memory model allows us to observe the patient’s jaw from multiple angles, and a series of measurements and calculations to help develop a treatment plan. Intraoperative study models help us understand the effectiveness of treatment to determine the next step in the program. Working models are necessary for making certain braces. Postoperative memory storage model to facilitate the comparative analysis of the efficacy of preoperative and postoperative. 2.Photographs Before and after surgery, the doctor will make a photo record of the patient. Photographs have two functions. One is the role of diagnosis, the patient can be observed and measured in the photo. The second is the role of the file, the effect of treatment, with photos, both doctors and patients have a basis. 3.X-ray film X-rays can help us understand the situation inside the bone which cannot be seen by the naked eye. Above this is called surface tomography also called panoramic film, in this X-ray film can see all the upper and lower teeth and upper and lower jaw. This is the most basic requirement for orthodontic treatment, if even this X-ray is not available, it is difficult to carry out orthodontic treatment because it is not possible to understand the situation of the root of the teeth in the bone. This is called lateral cephalometric film, which can understand the comprehensive situation and interrelationship between the anterior-posterior and vertical directions of the maxillary and mandibular skull, and measurements can be made to provide scientific basis for clinical diagnosis and evaluation. This is a joint film, which is mainly used to understand the situation related to joints. 4, Oral CT In recent years, dental CT has been developed, which can understand the craniomaxillofacial tissues, especially the hard tissues, from any angle and at any level, and it can be reconstructed in three dimensions, so that the doctor can obtain more and more accurate information. The CT above shows the patient’s blocked teeth from multiple angles. Dental CT is less radioactive and less expensive than traditional CT, and is being used more and more. What patients should know is that while we do not advocate unnecessary tests and the above x-rays are not necessary for everyone to use every item, they should be used when they are needed. Otherwise, there is some critical information that the doctor is not informed of, and orthodontic treatment becomes a blind man riding a blind horse, which can be very dangerous.