Year : 2007 | Volume
: 18 | Issue : 3 | Page : 138--140
Mesiodens with an unusual morphology and multiple impacted supernumerary teeth in a non-syndromic patient
Pavithra Srivatsan, N Aravindha Babu
Department of Oral Pathology, Sree Balaji Dental College and Hospital, Chennai, India
Department of Oral Pathology, Sree Balaji Dental College and Hospital, Chennai
Supernumerary teeth are a relatively frequent disorder of odontogenesis characterized by an excess number of teeth. Mesiodens is the most common type of supernumerary tooth found in the premaxilla between the two central incisors. They can be supplemental (resembling natural teeth), conical, tuberculate or molariform. We present the case of a 19 year-old girl who presented with a mesiodens of an unusual morphology and multiple impacted supernumerary teeth not associated with any syndrome.
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Srivatsan P, Aravindha Babu N. Mesiodens with an unusual morphology and multiple impacted supernumerary teeth in a non-syndromic patient.Indian J Dent Res 2007;18:138-140
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Srivatsan P, Aravindha Babu N. Mesiodens with an unusual morphology and multiple impacted supernumerary teeth in a non-syndromic patient. Indian J Dent Res [serial online] 2007 [cited 2021 Nov 30 ];18:138-140
Available from: https://www.ijdr.in/text.asp?2007/18/3/138/33792
Supernumerary teeth are a developmental disturbance occurring during odontogenesis resulting in the formation of teeth in excess of the normal number. They occur both in the deciduous and permanent dentition. The first report of a supernumerary tooth appeared between AD 23 and 79.  The prevalence of hyperdontia in various populations is reportedly between 0.1-3.8% with a male to female ratio of 2:1.  They occur more commonly in the permanent dentition (prevalence of 0.10-3.6%) when compared to the primary dentition (prevalence of 0.02-1.9%). 
Supernumerary teeth can be classified based on the time of appearance; according to the position arch; and according to their shape. 
Supernumerary teeth may be single, multiple, unilateral or bilateral, erupted or unerupted and in one or both jaws. Among the supernumerary teeth, mesiodens is the most common type.  The term mesiodens refers to a supernumerary tooth present in the premaxilla between the two central incisors. Mesiodens are more common in the permanent than in the primary dentition. The incidence of occurrence of mesiodens is 0-1.9% for deciduous teeth and between 0.15-3.8% for permanent teeth with male to female occurrence ratio of 2:1.  Mesiodens can present morphologically as a cone-shaped tooth (most common), tuberculate or molariform. We report a case of a mesiodens with an unusual morphology in a 19 year-old girl with multiple impacted supernumerary teeth.
A 19 year-old female reported with a complaint of forwardly placed teeth [Figure 1]. Intraoral examination revealed a mesiodens with an abnormal morphology between the right permanent maxillary central incisor and a partially erupted, rotated left permanent central incisor [Figure 2]. The incisal aspect of the mesiodens exhibited four cusp-like structures with caries. The left permanent maxillary lateral incisor and canine were labially placed.A supplemental tooth resembling the permanent lateral incisor was seen on the palatal aspect of the permanent lateral incisor [Figure 3].
The premolars and molars were in normal alignment. A full complement of teeth was seen in the lower arch [Figure 4]. Soft tissues were normal. There was no relevant medical and family history and the patient was otherwise healthy. Routine radiographic investigations were carried out to evaluate the status of the teeth. The orthopantomogram revealed ten supernumerary teeth, one erupted mesiodens, a supplemental lateral incisor in the maxilla and eight impacted teeth in the mandible (one canine and two premolar-like supplemental teeth on each side and a distomolar in the right and left quadrants) [Figure 5]. In view of the multiple impacted supernumerary teeth, a clinical examination was done to rule out syndromes associated with multiple impacted supernumerary teeth.
The patient was normal in her facial appearance, did not exhibit any physical or skeletal abnormality and showed no signs of mental retardation. Chest and skull radiographs revealed no abnormalities. Since the patient did not have siblings, her parents were advised panoramic radiographs to rule out impacted supernumeraries. Their panoramic radiographs did not reveal any impacted supernumeraries. The case was referred to the department of Oral surgery and Orthodontia for further management. The mesiodens and the impacted teeth were extracted and the case was managed orthodontically.
It was originally postulated that mesiodens represented a phylogenetic relic of extinct ancestors who had three central incisors.  A second theory known as dichotomy suggests that the tooth bud is split to create two teeth, one of which is the mesiodens.  The third theory involving hyperactivity of the dental lamina is the most widely supported.  According to this theory, remnants of the dental lamina or palatal offshoots of active dental lamina are induced to develop into an extra tooth bud, which results in a supernumerary tooth.
Genetics are also thought to contribute to the development of mesiodens as such teeth have been diagnosed in twins, siblings and sequential generations of a single family.  Autosomal dominant inheritance with incomplete penetration has been the proposed genetic theory. A sex-linked pattern has also been proposed as males are affected twice as frequently as females. Anomalous proliferation of the external epithelial layer of the enamel has also been proposed as one of the aetiological factors.  Mesiodens can be classified on the basis of their occurrence in the permanent dentition (rudimentary mesiodens) and according to their morphology (conical, tuberculate or molariform).  Supplemental mesiodens resemble natural teeth in both size and shape whereas rudimentary mesiodens exhibit abnormal shape and smaller size. Conical mesiodens are generally peg-shaped and are located palatally between the maxillary central incisors. They have a completely formed root and can erupt into the oral cavity. However, they may also be inverted with the crown pointing superiorly in which case they are less likely to erupt into the oral cavity.  Tuberculate mesiodens are barrel-shaped with several cusps or tubercles and have incomplete or abnormal root formation. They rarely erupt into the oral cavity. A much rarer type of mesiodens is the molariform mesiodens, which has a premolar-like crown and a completely formed root. 
In the present case, the mesiodens was rotated with the labial aspect placed mesially and the palatal aspect distally [Figure 6]. The incisal / occlusal aspect presented three grooves with three cusp-like structures on the labial half and a single cusp-like structure on the palatal half [Figure 7]. The palatal and labial surfaces resembled a central incisor [Figure 8],[Figure 9]. The mesiodens in this case had an abnormal incisal morphology. Developmentally, anterior teeth develop from four lobes, three on the labial and one on the lingual / palatal represented by the cingulum.  In our patient, there were three cusp-like structures on the labial aspect and a cingulum-like structure on the palatal aspect corresponding to the four lobes from which the tooth would have developed. Intraoral periapical radiograph revealed a single conical root with a single root canal [Figure 10].
We propose that a lack of fusion of the lobes during development probably gave rise to a mesiodens with an abnormal morphology. The cases of nonsyndromic multiple impacted supernumerary teeth as in our patient are more likely to occur in patients whose relatives also possessed supernumeraries, although inheritance does not follow a simple Mendelian pattern.  In our case, there was no familial tendency for multiple impacted supernumerary teeth. The present case is rare due to the presence of a mesiodens with an unusual morphology with multiple impacted supernumerary and supplemental teeth in a nonsyndromic patient.
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