At the end of orthodontic treatment, the teeth are maintained in their position in the alveolar bone by wearing retainers, which are removed after the bone remodeling is completed. After removing the aligners, the teeth lose their traction and archwire restriction, and may shift, so wearing retainers can be a good way to limit the rebound of the teeth and maintain the orthodontic effect. Nowadays, the commonly used retainers include transparent pressure film retainers, abutment lip arch type retainers, lingual wire retainers, etc. The retainers should be worn for one and a half years. Retainers should be worn for about one and a half to two years, and when the teeth are severely twisted or when there is a large gap, a longer period of time is needed. It is important to pay attention to the cleaning and hygiene of the retainers, and not to sterilize the retainers with hot water or chemicals, so as to avoid deformation.