Signs and Symptoms - Chewing difficulty and damage to adjacent structures - Deviation in occlusion - Asymmetry of dental arch due to enlarged crown - Aesthetic problem - Delay or obstruction of adjacent tooth eruption

Cause - Unknown cause, but possible factors include vitamin deficiency, hormonal irregularities, infection or inflammation near developing tooth bud, drug-induced, genetic predisposition, and radiotherapy damage to tooth germ

Mechanism - Gemination occurs when two teeth develop from one tooth bud, resulting in an extra tooth - Fusion is the union of two normally separated tooth germs, which can be complete or incomplete - Geminated teeth have incomplete division, resulting in a large tooth crown with a single root and canal - Gemination is an asymptomatic condition - Prevalence of gemination or fusion is 2.5% in primary dentition and 0.1-0.2% in permanent dentition

Diagnosis - Clinical examination - Radiographs showing two crowns arising from a single root

Treatment - Maintain good oral hygiene to prevent plaque accumulation - Use fissure sealants and resin restorations to prevent dental caries in deep grooves and fissures - Consider orthodontic treatment - Reshape and restore teeth with appropriate materials - Perform root canal treatment, followed by reduction of medio-distal width and crown restoration - Surgical division of the tooth into two teeth if root canal treatment is not suitable - Extraction may be considered if the tooth is not suitable for root canal treatment, followed by fixed or removable prosthetic if needed - Transplantation of supernumerary teeth to replace the geminated tooth - Thorough knowledge of root canal morphology is necessary to avoid complications before root canal treatment or extraction

Related abnormalities of the dentition - Amelogenesis imperfecta - Dentinogenesis imperfecta - Hyperdontia (more than average number of teeth) - Anodontia (lack of tooth development)