Large gaps between teeth can be seen in the following situations: 1. If large gaps occur in the absence of missing teeth, they may be due to periodontal disease. In particular, scattered fan-shaped gaps in the front teeth may be due to alveolar bone loss, gingival recession, less and less tooth-supporting tissues, and the gap will become larger and larger under the impetus of occlusal force and forward movement of the tongue; 2. If the patient develops obvious tooth loss, the gap will also increase. With the prolongation of time missing teeth gap is not dealt with, may be both sides of the teeth will fall to the center, the opposite side of the teeth to the missing teeth gap elongation, resulting in the whole occlusal state disorder; 3, congenital gap: teeth eruption after the absence of missing teeth, there is no periodontal disease, the patient appeared to have a large gap between the teeth, this is the case of the maxillary and mandibular bone is greater than the width of the teeth that is greater than the tooth volume. These patients are often treated with orthodontic treatment to close the excess gap. The doctor will decide whether the front teeth are inward or back teeth are forward based on the patient’s facial shape, occlusal status, and cephalometric films. Therefore, if a patient has a gap between the teeth, he or she should go to the hospital early to determine the problem of the gap and solve the problem accordingly depending on the situation.