Retainers are supposed to keep after orthodontic treatment. Depending on the degree of malocclusion, there are generally no retention, limited retention, and long term retention, and it is recommended to follow the advice of your medical professional. 1. No retention: Retention is partially unnecessary after functional orthodontic treatment in early childhood. 2. Limited retention: Most orthodontic treatment is usually for 1-2 years. In the first year, it is recommended to wear the retainer all day long except for removing it when eating or drinking, and in the second year, it can be worn at night. 3. Long-term retention: Some teeth that are thin or have undergone arch expansion will be retained for a relatively longer period of time. Adults mostly have long-term retention. Every patient’s oral condition before orthodontic treatment is different and there are individual differences. It is recommended to follow the orthodontist’s advice to choose the wearing time.