Lower teeth against the medial side of the upper teeth in the vertical and horizontal directions are called overjaw and override relationships, respectively, and are normal in the labial aspect of the lower anterior teeth against the lingual aspect of the upper teeth. 1. Overjet. Under normal circumstances, the maxillary anterior teeth over the lip surface of the mandibular anterior teeth no more than cut 1/3, and the incisal edge of the mandibular anterior teeth to be in the maxillary anterior teeth within the lingual cut 1/3. When the maxillary anterior teeth cover the labial surface of the mandibular anterior teeth more than the incisal 1/3, it is called deep overjet. 2. Coverage. Under normal circumstances, the horizontal distance from the incisal edge of the maxillary incisors to the labial surface of the mandibular incisors is within 3 millimeters. However, when the horizontal distance from the incisal edge of the maxillary incisor to the labial surface of the mandibular incisor exceeds 3 millimeters, it is called deep overjet, which causes teeth and lips to protrude forward depending on the degree of severity. The normal situation is that the lower teeth are against the inner side of the upper teeth. If the upper teeth are against the inner side of the lower teeth, it means that there is anti-maxilla, and you need to go to the hospital for orthodontic treatment in time.