Case Report

Three siblings (two male, one female) applied to the department of Oral Diagnosis and Radiology Clinic at the faculty of Dentistry at Ataturk University with complaints of toothaches, aesthetic and functional problems. In their clinical and radiographic examination, we determined more missing teeth (oligodontia). In their history, a systemic disease or syndrome was not determined, and it was discovered that hypodontia presented their father paternally. Oligodontia was found in these three siblings. Of which one is a girl (Ö.T., 13 years old), and two are boys (M.T., 11 years old and B.T., 5 years old). In the case of Ö.T., except for the third molars, 12 permanent teeth are in place, and 16 permanent teeth are absent. Missing teeth are 12, 14, 15, 17, 22, 24, 25, 27, 31, 32, 35, 37, 41, 42, 45, 47 numbers teeth (fig. 1).

Figure 1

Figure 1: Panoramic radiography of Ö.T. 16 permanent teeth are absent.

In the case of M.T., except for the third molars again, 4 permanent teeth are existent, where as 24 permanent teeth are absent. The missing teeth numbers are 11, 12, 13, 14, 15, 17, 21, 22, 23, 24, 25, 27, 31, 32, 33, 34, 35, 37, 41, 42, 43, 44, 45, 47 (fig. 2).

Figure 2

Figure 2: Panoramic radiography of M.T. 24 permanent teeth are absent.

In B.T.'s case, except again for the third molars, 10 permanent teeth are intact, while 18 permanent teeth are absent. The Missing teeth numbers are 12, 13, 14, 15, 22, 23, 24, 25, 31, 32, 33, 34, 35, 41, 42, 43, 44, 45, numbers teeth (fig. 3).

Figure 3

Figure 3: Panoramic radiography of B.T. 18 permanent teeth are absent.

The teeth that were present were carious, and had malposition along with polidiestema in each of the cases.

Discussion

A tooth is defined to be congenitally missing if it has not erupted in the oral cavity and is not visible in a radiography.₁ In general hypodontia is the term most frequently used when describing the phenomenon of congenitally missing teeth.₂ Hypodontia is an anomaly that may result in dental malpositioning, periodontal damage, lack of development of maxillary and mandibular bone height and has significant psychological, aesthetic and functional consequences.₃ Hypodontia and oligodontia are classified as isolated or non-syndromic, where as hypodontia/oligodontia and syndromic hypodontia/oligodontia or hypodontia/oligodontia are associated with syndromes.₂ In the recent years, the following definitions have been used.

• Hypodontia:1 to 6 teeth missing (excluding third molars)

• Oligodontia: more than six teeth missing (excluding the third molars)

• Anadontia: complete absence of teeth.2,4

In the cases we studied, missing teeth excluding the third molars was found in more than six cases without any systemic disorders or syndrome. Thus, congenital lack of one or more permanent teeth without any systemic disorders or syndrome was suggested isolated or non-syndromic hypodontia/oligodontia.

Hypodontia is a common trait in modern populations and it is often encountered by dental practicioners.₅ The use of panoramic radiography is recommended, together with clinical examination for the detection or confirmation of dental development and performing the diagnosis of the hypodontia. Missing teeth are recognized by identifying and counting the existing teeth. However, it must be kept in mind that the development of teeth may vary markedly among patients.₁,₂

The prevalence of permanent tooth agenesis ranges between 1.6% and 9.6%, and it reaches 20% if the third molars are considered. The prevalence in primary dentition is lower, ranging between 0.5% and 0.9%.₆,₇ Although tooth agenesis is occasionally caused by environmental factors, in the majority of cases hypodontia has a genetic basis. Developing teeth are affected by environmental factors such as multiagent chemotherapy, radiation therapy, fractures, surgical procedures on the jaws, extraction of the preceding primary teeth, and lack of necessary space imposed by malformed jaws.₁,₂ In familial hypodontia, the type of inheritance in the majority of families seems to be autosomal dominant with incomplete penetration and variable expressivity.₈,₉ An autosomal recessive model of inheritance is also possible.₁₀,₁₁ Mutations in transcription factors MSX1 and PAx9 have been identified in families with an autosomal dominant oligodontia.₁₂Oligodontia, like hypodontia is seen as an isolated trait or as a part of a syndrome. Isolated oligodontia is inherited in an autosomal dominant form with reduced penetration. In our cases, oligodontia was also determined to the patient's kindred via their family history. Therefore, from analyzing the cases, we suggest isolated oligodontia without any systemic disorders or syndromes may be inherited as an autosomal dominant trait.

Oligodontia and hypodontia have similar associated anomalies. Several dental anomalies have been reported together with congenitally missing teeth. Examples of these are delayed formation and eruption of teeth, reduction in tooth size and form, malposition of teeth (ectopic maxillary canines and ectopic eruption of other teeth), infraposition of primary molars, teeth with short roots, taurodontism, rotation of premolars and or maxillary lateral incisors, enamel hypoplasia, hypocalcifation and dentinogenesis imperfecta.₁₃,₁₄,₁₅,₁₆

In the cases studies the remaining teeth were carious, had malposition, polidiestema and malformation. No definite etiologic relationship has been found between hypodontia and systemic diseases or endocrine disturbances.₁₀,₁₁

Dental manifestations are seen in several syndromes together with malformations of other organs. Some of the best known of these syndromes are isolated cleft lip/palate, Pierre Robin sequence, Van der Woude syndrome, MSX1 mutation, hypohidrotic ectodermal dysplasia (EDA or HED), Ectrodactyly- ectodermal dysplasia-clefting syndrome(EEC), Cleft lip palate ectodermal dysplasia syndrome(CLPED1), incontinentia pigmenti (IP,Bloch–Sulzberger Syndrome), Hypohidrotic ectodermal dysplasia and immune deficiency (HED-ID), Oral facial digital syndrome type I (OFD1), Witkop tooth-nail syndrome, Fried syndrome, Böök syndrome (PHC), Hair- nail- skin- teeth dysplasias, Rieger syndrome, Holoprosen cephaly, Down's syndrome (trisomi 21), Wolf- Hirschhorn syndrome (deletion 4p), Kabuki syndrome, Diastrophic dysplasia (DTD), Hemifacial microsomia and Recessive incisor hypodontia(RIH).₁₇,₁₈,₁₉,₂₀,₂₁,₂₂,₂₃,₂₄,₂₅,₂₆,₂₇,₂₈

In conclusion, missing teeth, abnormal occlusions or altered facial appearance may cause some patients psychological distress. If the extent of hypodontia is mild, the associated changes may likewise be slight and manageable by orthodontists. In more severe cases restorative implants and prosthetic procedures can be undertaken. Thus, the concept of early diagnosis of these patients becomes more important. When a case of tooth agenesis is seen, the presence of the anomaly should be recorded with a complete clinical history including panoramic radiograms and models, for proper phenotype characterization prior to any surgical or orthodontic treatment.

Correspondence to

bcakur@atauni.edu.tr