Journal of Indian Society of Pedodontics and Preventive Dentistry
Journal of Indian Society of Pedodontics and Preventive Dentistry
                                                   Official journal of the Indian Society of Pedodontics and Preventive Dentistry                           
Year : 2008  |  Volume : 26  |  Issue : 6  |  Page : 79--81

A rare case of concomitant hypo-hyperdontia in identical twins

A Sharma 
 Department of Pedodontics, Seema Dental College and Hospital, Rishikesh-249 203, Uttarakhand, India

Correspondence Address:
A Sharma
A/17, HIHT Campus, Jolly Grant, P.O.-Doiwala 248 140, Dehradun, Uttarakhand


Concomitant hypodontia and hyperdontia is a rare condition of unknown etiology. One such case of occurring in identical twins in mixed dentition is presented and discussed. A sibling, especially a twin of an affected patient, should be suspected of having a similar problem, even if he or she is asymptomatic. Genetic factors probably play an important etiological role in the co-occurence of partial anodontia and supernumerary teeth.

How to cite this article:
Sharma A. A rare case of concomitant hypo-hyperdontia in identical twins.J Indian Soc Pedod Prev Dent 2008;26:79-81

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Sharma A. A rare case of concomitant hypo-hyperdontia in identical twins. J Indian Soc Pedod Prev Dent [serial online] 2008 [cited 2021 Apr 12 ];26:79-81
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Concomitant hypo-hyperdontia is a condition where congenital absence of teeth and an excess number of teeth are present in the same individual. It is a very rare condition, with only few case reports in the literature. [1],[2],[3],[4],[5],[6],[7],[8],[9],[10],[11] It has been found more often in the permanent dentition than in the primary or mixed dentition. [12] Though its etiology is unknown, disturbances in migration, proliferation, and differentiation of the neural crest cells and interactions between the epithelial and mesenchymal cells during the initiation of odontogenesis have been suggested as possible causes. [12],[13]

Presented here is the first such case to be reported in identical twins in mixed dentition.

 Case Report

A 7-year-old male, accompanied by his father reported to the department of pedodontics with the complaint of a tooth seen to be erupting since the last 3 months behind the upper front teeth and causing difficulty while speaking. A review of his family and medical histories showed nothing remarkable though it revealed that the patient had a twin brother. No abnormality was noted during the general physical /extraoral examination. Intraoral examination [Figure 1] showed a palatally erupting tuberculate mesiodens in relation to 61. Radiographic examination [Figure 2] and [Figure 3] revealed bilateral presence of two tuberculate mesiodentes, one erupted and causing rotation of 21, while the other was seen impacted in relation to 51. the maxillary left second premolar was found to be missing. The erupted mesiodens was extracted.

The patient and the parent were given a detailed explanation regarding the condition and advised follow-up every 2 months; they were also asked to bring the brother at the next visit. The father was made aware of the possibility of a similar situation in the other twin. However, it was after a year had elapsed that he visited the department with both the children, who were seen to be identical twins [Figure 4].

Now complained of the other erupting tooth hindering tongue movements, though it had become visible in the mouth 10 months back. Intraoral and radiographic examination [Figure 5] and [Figure 6] showed a palatally erupting tuberculate mesiodens in relation to 51; it was extracted along with the primary maxillary central incisors.

Dental history of the twin brother revealed that he had a maxillary midline supernumerary tooth which was erupting since the last 2 months. Clinical and radiographic examination showed a tuberculate mesiodens between the primary central incisors [Figure 7] and [Figure 8]. The mandibular left second premolar was observed to be missing [Figure 9]. The retained 51, 61, 81, and mesiodens were extracted. Both the brothers were kept on 6-monthly recall.


Human dental eruption is known to be a dynamic interaction between heredity and environment. It is widely assumed that the development of supernumerary teeth or congenitally missing teeth may involve a genetic factor and, hence, may show a familial tendency. [11],[14],[15] Monozygotic / identical twins showing discordance for expression of hypodontia or hyperdontia have also been reported. [16],[17] The co-occurrence of supernumeraries and partial anodontia in the present case suggests its genetic predisposition, as it is axiomatic that the identical twins have same genotypes. The variable expression of the concomitant condition in the twins is however notable and thus makes them a discordant pair.

Cases exhibiting absent premolars associated with a mesiodens were noted by Mercer, [5] Nathanail, [4] and Gibson. [7] But the case reported here is unusual, as tuberculate mesiodentes in relation to the primary central incisors is a rare occurrence. Supernumeraries in primary dentition are usually normal (supplemental type) or conical in shape. A tuberculate supernumerary tooth rarely erupts in childhood. [18]

During the mixed dentition years, treatment planning should be based on the dental age rather than the chronological age of the patient, hence case was kept under observation. Good quality premolars seldom form after the child is 8 years of age. [19] Early diagnosis of absence of teeth can reduce orthodontic complications and assist in treatment planning. A thorough evaluation of facial profile, incisor position, space requirements, and the status of the primary teeth is crucial to determine the correct treatment for congenitally missing permanent teeth. Early diagnosis of mesiodentes allowed an early conservative intervention and thus a more favorable prognosis.


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