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Double teeth

Sir, we would like to share with your readers an unusual case of a patient with double teeth. The 18-year-old male presented with inflammatory episodes in the right molar area, in relation to the partially erupted right third molar. Clinical and radiographic examination revealed gemination of the right third mandibular molar (Fig. 1). This tooth was removed entirely under local anaesthesia without odontosection (Fig. 2).

Figure 1
figure 1

Orthopantomograph showing 'double teeth' mandibular right third molar

Figure 2
figure 2

Clinic image of tooth after exodontia. A: occlusal view. B: apical view. C: lingual view. D: buccal view

The anomaly of conjoined teeth has been described by different terms, such as gemination, fusion, double teeth and twining. These definitions of fusion or gemination are based on the way the tooth was developed. Gemination occurs as a result of attempted division of a single tooth germ, whereas fusion arises through the union of two normally separated tooth germs. Differential diagnosis is difficult; therefore several authors use the term 'double teeth'.1 This pathology usually involves anterior teeth, and is uncommon in premolars and permanent molars.1

The aetiology of gemination remains uncertain. Environmental factors, traumatisms, systemic diseases, vitamin deficits or genetic predisposition have been proposed for its development.2,3

Double teeth are generally asymptomatic. However, teeth may cause clinical and aesthetic problems, loss of the arch length, delayed or ectopic permanent teeth eruption, and periodontal diseases.4

Treatment is different between deciduous and definitive dentition. Exodontia is indicated when the anomalous deciduous tooth causes a permanent tooth altered eruption. Treatment in definitive double teeth depends on type, position in the dental arch and possible alterations affecting adjacent teeth. Exodontia, endodontics and aesthetics can be indicated.1,2,3 Surgical removal of the tooth and the paradental cyst is considered the treatment of choice when the involved tooth is a third molar. In our case, tooth extraction was indicated because of a lack of space and pericoronaritis episodes.


  1. Olivan-Rosas G, López-Jiménez J, Giménez-Prats M J et al. Considerations and differences in the treatment of a fused tooth. Med Oral 2004; 9: 224–228.

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  2. Chen H S, Huang Y L . Fusion of third and fourth mandibular molars? Oral Surg Oral Med Oral Pathol 1992; 73: 767.

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  3. Tomizawa M, Shimizu A, Hayashi S et al. Bilateral maxillary fused primary incisors accompained by succedaneous supernumerary teeth: report of a case. Int J Paediatr Dent 2002; 12: 223–227.

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  4. Duncan W K, Helpin M L . Bilateral fusion and gemination: a literature analysis and case report. Oral Surg Oral Med Oral Pathol 1987; 64: 82–87

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Méndez, P., Junquera, L. & Gallego, L. Double teeth. Br Dent J 202, 508–509 (2007).

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