1. Breaking bad oral habits: Biting lips, spitting out tongue and other bad oral habits must be completely broken before the retainer is removed. ?

2. Early treatment: Orthodontic treatment can achieve a stable effect during the period of vigorous growth and development of the jaw. For cases such as tooth distortion, early treatment is recommended. ?

3. Sometimes, after treatment, if the mechanical retention can't reach the natural retention, the fibers around the tooth neck should be cut off to obtain stable results, which can reduce the retention time. ?

4. Orthognathic surgery: It is difficult to improve malocclusion only by mechanical correction, and it is often necessary to cooperate with surgical treatment, such as mandibular protrusion deformity and opening and closing deformity. ? 5. Permanent retention: In some cases, prolonged wearing of retention can not prevent recurrence, such as abnormal nail-shaped lateral incisors, space between upper and middle incisors, severe tooth distortion, and loss of permanent teeth. Fixed restorations such as crowns and bridges or removable partial dentures are usually used as permanent retention in clinic.