Deep overjet is caused by abnormal development of the dental arch and jawbone, and is categorized into dental and osseous, with different clinical manifestations and treatment modalities. 1. Dental deep overjet: It is mainly manifested as simple deep overjet of the front teeth, scattered gaps in the upper front teeth, and the shape and size of the upper and lower jaws are normal. If the symptoms are mild, orthodontic treatment can be carried out by wearing braces; if the condition is serious, dental implants can be placed on the alveolar bone to control the movement of teeth. 2. Bone deep overjet: It is mainly manifested by the abnormal size, shape or positional relationship between the upper and lower jaws in the three-dimensional direction. If the symptom is mild, it can be corrected by applying supportive nails and extra-oral arches; if the condition is serious, orthognathic surgery can be used for treatment. When patients experience discomfort, they should go to the hospital immediately.