Children and adolescents will go through the period of tooth replacement. During the process of tooth replacement, the incisors will usually have some gaps, usually not more than 3mm, which are normal temporary misalignment during the period of tooth replacement and do not need to be corrected. The gap will gradually disappear with the completion of tooth replacement. If it is found that the gap between the incisors of children or adolescents is very large, the following reasons should be considered: 1, extra teeth between the incisors: that is, an extra tooth grows between the incisors, sometimes it can be seen directly by the naked eye, but sometimes the extra teeth are buried between the roots of the two incisors and need to be found by taking X-rays; 2, the upper lip tethering attachment is too low: if the upper lip tethering attachment position is low, in the process of the normal activity of the mouth and lips, it will produce a tooth splitting This slow and long-term force will also cause the gap between the incisors to separate; 3, abnormalities in the process of tooth replacement: such as abnormal position of permanent teeth development or disruption of the development sequence, will also produce the gap between the incisors; 4, abnormal tooth development: the width of the incisors is too narrow, but the width of the dental arch is normal, leaving a gap between the two teeth; 5, bad habits: including the habit of biting the lower lip or spitting out the tongue, this long-term slow force will make the teeth shift, the incisors tilt forward and spread out, creating gaps. If children are found to have gaps in their incisors, they should be seen by a professional oral health care provider who can determine the cause and then remove the cause. Excessive incisor gaps can be corrected with simple orthodontic treatment.