Crown lengthening is a surgical procedure that lowers the gingival margin, exposing healthy tooth structure and lengthening the clinical crown to facilitate restoration or address aesthetic concerns. Any procedure has damage, and crown lengthening is no exception, so it should be performed with minimal damage and after-effects. The common sequelae of crown lengthening are as follows: 1, improper selection of indications, excessive removal of gingiva and alveolar bone during surgery leads to loosening of the tooth resulting in tooth extraction; 2, insufficient removal of gingiva and alveolar bone during surgery, the postoperative broken end is not fully exposed to meet the requirements of restoration, requiring another surgery; 3, postoperative gingival recession, the appearance of a black triangle in the anterior region affects the aesthetics; 4, gingival recession leads to root surface exposure, hot and cold sensitivity, fear of cold 5, the postoperative emergence of dental embedding obvious; 6, uneven gingival removal, postoperative gingival asymmetry, unsightly; 7, the restoration of clinical crowns appear too long and unattractive.