The lingual side aligner is to place the aligner on the inner side of the teeth (lingual side), compared with the traditional aligner placed on the outer side of the teeth (labial side), it cleverly hides the aligner, which not only achieves the ultimate goal of orthodontic treatment, but also completely avoids the pain of braces exposure. Compared with the traditional aligners, its advantages are as follows: 1. Highly invisible: the aligners in the lower or upper jaw can only be seen when the head is bowed or tilted up for a laugh, and generally cannot be seen under other circumstances. 2, more conducive to aesthetics: the traditional labial side aligners cause chalky demineralization on the outer surface of the teeth (lip and cheek surfaces) due to the patient’s poor maintenance of oral hygiene and other factors, which seriously affects the aesthetics, and the lingual side aligners, because they are located on the inner side of the teeth, do not affect the cleanliness of the outer surface of the teeth. 3.Personalized service: bracket indirect bonding technology, so that the brackets are more accurately positioned on the teeth.