I. Clinical data Application of triple pin spring correction of upper mesiodistal incisor torsion during the replacement period in 26 cases, a total of 43 torsion teeth, of which 10 cases were male and 16 cases were female, aged 7 to 13 years old, with an average age of 9 years old. There were 14 cases of bilateral symmetric torsion, with torsion angles ranging from 10° to 70°, of which 30° to 45° was the most, 12 cases; 9 cases of unilateral torsion, with torsion angles ranging from 30° to 90°, of which 7 cases were at angles of 60° to 90°; and 3 cases of bilateral asymmetric torsion. Second, the orthodontic method 1, orthodontic appliance design: the orthodontic appliance consists of two transverse tubes and a triple pin spring glued on the surface of the mesial incisors. The inner diameter of the transverse tube is 0.5mm, which can be truncated from the pin tube, about 5-6mm long, and directly glued in the middle of the crown of the upper mesial incisor labial surface with enamel adhesive, which is perpendicular to the tooth’s long axis; it can also be welded on the labial surface of the mesial incisor with a ring. Triple pin spring is made of 0.5mm diameter stainless steel wire bending (Figure 1), the transverse arm inserted in the transverse tube, so that it coincides; longitudinal arm length and crown length is equivalent to the length of the longitudinal arm and the transverse arm of the intersection of the angle of a right angle; three spring ring diameter of 2.0 ~ 2.5mm, the upper spring ring from the lips and cheeks of the grooves of 1 ~ 2mm, in the spring ring to let go of the tethers, does not affect the lip tether mobility. 2.Operation method: no force is applied at the initial wearing, and review after one week. The two transverse arms add force in the direction opposite to the direction of the twisted tooth, the angle of force is generally 10° ~ 15°, at this time the insertion of the transverse tube produces a torsion force of about 27.6 ~ 41.4g . The force is applied once a week, and the method of alternating the force between the two transverse arms can also be used to prevent the pin spring from branching out to the upper lip and causing mucosal damage. 3.Triple pin spring orthodontic technology is applied to patients with torsion of upper middle incisors during the period of tooth replacement, which is simple and economical, fast and reliable, with remarkable therapeutic effect. It only needs to bond the orthodontic appliance on the labial surface of the torsion crown, does not involve the whole dental arch and jawbone, does not need the support of the posterior teeth, and does not affect the normal growth and development of the children’s dental arch and jawbone, so it is suitable for the early orthodontic treatment of upper and middle incisal torsion during the period of mixed dentition, and prevents the occurrence of the crowding of the anterior teeth to a certain degree, and has unique efficacy within the scope of its applicability. When there is no sufficient gap between upper and middle incisors and lateral incisors, a small pin spring can be welded at the junction of upper 2/3 and lower 1/3 of the longitudinal arm of the triple pin spring, which pushes the lateral incisors to the distal center and solves the problem of insufficient gap. Ball, to prevent its compression of the gingival mucosa. 6, triple pin spring per reverse twisting force 10 °, will produce 27.6g / cm force, the pressure on the periodontal membrane is about 113g / cm2, usually considered the periodontal membrane to withstand the pressure of 120g / cm2 is the most safe and effective, so there is no damage to the periodontal tissues.