Children’s teeth in the middle of the seam have the following kinds of situations: 1, the upper lip tether attachment is too low, attached to the two incisors alveolar protrusion, after the attachment force is relatively low, the lip tether has a pulling effect, so that the middle of the teeth seam can not be closed; 2, teeth have ectopia, such as tooth alignment disorder, there is a kind of butterfly-like teeth ectopia formation, so that the middle of the teeth gap; 3, periodontal bad, one or two incisors periodontal problems Problems, easy to loosen, tilt, so that the gap between the two teeth formed; 4, two incisors in the middle of the buried multiple teeth, invisible to the naked eye, this situation must be taken to rule out, multiple teeth with occupancy, resulting in the inability to close. Therefore, the above four cases should be excluded, and the situation should be treated symptomatically and in a timely manner.