The manifestations of tooth deformity are various, and the degree of deformity is also different. There is mainly the deformity caused by single or combined abnormal tooth position and occlusal relationship. The common tooth deformities in daily life mainly include the following:
 
    1. Teeth crowding: teeth crowding is the phenomenon that the arch length of teeth can not accommodate all teeth arrangement, resulting in teeth dislocation and overlap. It is a common dental deformity in clinic. According to the degree of teeth crowding, it can be divided into three types: light, medium and heavy.
 
    2. Sparse dentition: the clinical manifestations of sparse dentition can be divided into two types: one is that the bone mass of alveolar bone is larger than teeth; the other is that there is gap between teeth. There are three situations of Sparse dentition :
      (1). The morphology of jaw is normal, but the tooth is too small or missing
      (2). The morphology of tooth is normal, but the jaw is too large
      (3). Loss of periodontal soft tissue
 
    3. Dentition irregularity: dentition irregularity includes many types of tooth deformities such as  teeth crowding, sparse dentition, abnormal occlusal relationship, abnormal skull shape.
 
   4. Malocclusion. Malocclusion refers to imperfect positioning of the teeth when the jaws are closed.
 
   5. Open Bite.  The open bite deformity is that there is a certain gap between the occlusal surfaces of upper and lower teeth without jaw contact relationship.
 

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