Some teeth can become loose with braces because the process of tooth realignment involves the resorption and reconstruction of the alveolar bone. If periodontal symptoms occur during this process without good oral hygiene, it can easily lead to resorption of the alveolar bone during the reconstruction process and loosening of the teeth, which is a common complication of cosmetic dentistry. Therefore, it is recommended to maintain good oral hygiene to control periodontal disease during the whole process of wearing braces for cosmetic dentistry, and to conduct active follow-up examinations to minimize the chance of tooth loosening. However, if there is bone resorption and tooth loosening, it is still necessary to undergo active treatment to control it.