Fusion occurs when normally separated tooth germs abnormally join together during development due to close proximity of the developing teeth or physical force acting on them. It results in a larger single tooth with either separate or fused root canals visible on radiographs. Fusion is commonly seen between anterior teeth or between a normal tooth and a supernumerary tooth. Diagnosis involves identifying a larger tooth associated with a missing adjacent tooth or seeing the union of dentin on radiographs. Treatment may require endodontic therapy and reshaping of the fused tooth.

1. Fusion

2. General information
• Embryonic union of normally separated to
germs
• It represents junction at the level of dentine
between juxtaposed normal tooth germs
• To separate developing tooth germs being
initially close together, as they grow and
expand their contact with each other and that
germs fuse to varying degrees

3. Aetiology
• Genetic – it is transmitted as an autosomal
dominant trait with reduced penetration
• Physical – physical force or pressure generated
during development causes contact of tooth
germs

4. Clinical features
• Common in anterior teeth
• It may occur between a normal tooth and a
supernumerary tooth such as mesio dens or
disto molar
• Tooth is almost twice in size than normal
• Separate or fused root canals

5. Radiographic features
• True nature and extent of the union will be
more evident of radiographs

6. Diagnosis
• Large tooth with missing adjacent tooth will
aid in diagnosis
• Fusion can be seen radiographically by dentine

7. Management
• Endodontic treatment
• Reshaping of tooth