1. Deep overbite of anterior teeth: also known as "pulling teeth", the anterior teeth protrude forward too long to exceed the lower teeth, which is a common malocclusion in clinic, often accompanied by deep overbite of anterior teeth.

2. Anterior crossbite: It looks like a "bulldog" in appearance, that is, the lower front teeth protrude forward or the upper front teeth are too backward.

3. Malocclusion: refers to the abnormality of tooth arrangement position and occlusion relationship. There are many manifestations of malocclusion. The common malocclusion is the dislocation of individual teeth, that is, one or more teeth in the dentition are out of position, such as inclined, tilted and twisted teeth.

4. Open jaw: it means that the front teeth or the back teeth can't bite vertically, and the cutting ends don't touch vertically, which can't reach the normal mandibular coverage distance. Normal overbite: the upper anterior teeth cover the lower anterior teeth 1/3- 1/2.

5, midline deviation: the midline of the upper anterior teeth is not aligned with the midline of the lower anterior teeth, which can be corrected by orthodontics.

6. Excessive tooth gap: a gap or gap between teeth in the oral cavity caused by tooth loss or missing teeth.

7. Crowded dentition: There are so many teeth that the mandible can't hold it.