Dental crowding is a very common clinical malocclusion and a common symptom for many patients who come to the hospital for consultation. Dental crowding, can be divided into mild dental crowding, moderate dental crowding and severe dental crowding. The specific orthodontic methods are as follows: 1, mild crowding: the method often used is not extracted orthodontic, through the fixed braces or invisible braces, to align the teeth for orthodontic treatment; 2, moderate crowding: according to the individual situation to decide whether to extract teeth. Some patients can choose not to extract teeth to correct, by pushing the teeth backward, or do adjacent slices cut to align the teeth, some patients may need to extract teeth; 3, most patients with severe crowding basically must be extracted to correct. After the extraction, in order to provide more space for the crowded teeth, so that other teeth that are crowded together can have their normal position and perform their functions. Crowded teeth have the option of orthodontic braces, either fixed braces, invisible braces, or lingual braces. Patients with severe crowding, because the crowded teeth often have poor self-cleaning ability, so the teeth are prone to decay or poorly cleaned teeth, bleeding gums and a series of other conditions. Therefore, patients with severe crowding can achieve not only aesthetic purposes but also healthier periodontals through orthodontics.