The phenomenon of tooth fusion arises through union of two normally separated tooth germs, and depending upon the stage of development of the teeth at the time of union, it may be either complete or incomplete. On some occasions, two independent pulp chambers and root canals can be seen. However, fusion can also be the union of a normal tooth bud to a supernumerary tooth germ. In these cases, the number of teeth is fewer if the anomalous tooth is counted as one tooth. In geminated teeth, division is usually incomplete and results in a large tooth crown that has a single root and a single canal. Both gemination and fusion are prevalent in primary dentition, with incisors being more affected.

Tooth gemination

Tooth gemination

The phenomenon of gemination arises when two teeth develop from one tooth bud and, as a result, the patient has an extra tooth, in contrast to fusion, where the patient would appear to be missing one tooth....

, in contrast to fusion, arises when two teeth develop from one tooth bud and, as a result, the patient has a larger tooth but a normal number.

Related abnormalities of the dentition

• Amelogenesis imperfecta
  Amelogenesis imperfecta
  Amelogenesis imperfecta presents with abnormal formation of the enamel or external layer of teeth. Enamel is composed mostly of mineral, that is formed and regulated by the proteins in it...
  
  
• Dentinogenesis imperfecta
  Dentinogenesis imperfecta
  Dentinogenesis imperfecta is a genetic disorder of tooth development. This condition causes teeth to be discolored and translucent. Teeth are also weaker than normal, making them prone to rapid wear, breakage, and loss. These problems can affect both primary teeth and permanent teeth...
  
  
• Hyperdontia
  Hyperdontia
  Hyperdontia is the condition of having supernumerary teeth, or teeth which appear in addition to the regular number of teeth.-Types:Supernumerary teeth can be classified by shape and by position...
  
   - More than the average number of teeth
• Anodontia
  Anodontia
  In dentistry, anodontia, also called anodontia vera, is a rare genetic disorder characterized by the congenital absence of all primary or permanent teeth. It is associated with the group of skin and nerve syndromes called the ectodermal dysplasias...
  
  - Lack of tooth development