Tooth gemination

Tooth gemination is a dental phenomenon that appears to be two teeth developed from one. There is one main crown with a cleft in it that, within the incisal third of the crown, looks like two teeth, though it is not two teeth. The number of the teeth in the arch will be normal.

Signs and symptoms

 * Misaligned teeth can lead to chewing difficulty and damage adjacent structures
 * Occlusion affected, causing deviation
 * Asymmetry of the dental arch due to enlarged crown
 * Aesthetic problem
 * Delay or obstruct the eruption of adjacent tooth
 * Tooth anatomy making the surface hard to clean and increase susceptibility of dental decay and periodontal disease

Cause
The cause of gemination is still unknown. However, there are a few possible factors contributing to gemination:
 * Vitamin deficiency
 * Hormonal irregularities
 * Infection or inflammation of areas near to the developing tooth bud
 * Drug induced
 * Genetic predisposition
 * Radiotherapy that caused damage to the developing tooth germ

Mechanism
The phenomenon of gemination arises when two teeth develop from one tooth bud, resulting in an extra tooth for the patient. In contrast, fusion occurs when two normally separated tooth germs unite, making it appear as if the patient is missing a tooth. Fused teeth can form through the union of two normally separated tooth germs, which can be either complete or incomplete, depending on the stage of development at the time of union. Occasionally, two independent pulp chambers and root canals can be observed. However, fusion can also occur between a normal tooth bud and a supernumerary tooth germ. In these cases, the number of teeth remains normal, making differentiation from gemination very difficult, if not impossible. In geminated teeth, division is usually incomplete, resulting in a large tooth crown with a single root and a single canal. It is an asymptomatic condition

The prevalence of gemination or fusion is 2.5% in primary dentition, and 0.1–0.2% in permanent dentition. It is more frequently observed in primary than permanent dentition; anterior than posterior teeth; unilaterally than bilaterally. It commonly occurs in the primary upper incisors.

Diagnosis

 * Clinical examination
 * Radiographs – shown as two crowns arising from one single root

Treatment
Before root canal treatment or extraction are carried out, the clinician should have thorough knowledge about the root canal morphology to avoid complications.
 * Patient should be advised to maintain a good oral hygiene to prevent plaque accumulation.
 * Fissure sealants and resin restorations for deep grooves and fissures to prevent dental caries.
 * Orthodontic treatment
 * Reshape and restore teeth with appropriate material.
 * Root canal treatment, followed by the reduction of medio-distal width of the tooth. Restore teeth with crown.
 * Root canal treatment then surgically divide the tooth into two teeth.
 * If the tooth is not suitable for root canal treatment, then extraction could be considered. Fixed or removable prosthetic may be needed after extraction.
 * Transplantation of supernumerary teeth to replace the geminated tooth.

Related abnormalities of the dentition

 * Amelogenesis imperfecta
 * Dentinogenesis imperfecta
 * Hyperdontia – More than the average number of teeth
 * Anodontia – Lack of tooth development