Year : 2005 | Volume
: 15 | Issue : 1 | Page : 69--72
Mesiodens presenting as a dentigerous cyst : Case report
SB Grover, P Singh, VP Venkatachalam, N Hekha
Departments of Radiology & Imaging and Otolaryngology, Vardhman Mahavir Medical College and Safdarjang Hospital, New Delhi - 110029, India
S B Grover
E-81, Kalkaji, New Delhi-110019,
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Grover S B, Singh P, Venkatachalam V P, Hekha N. Mesiodens presenting as a dentigerous cyst : Case report.Indian J Radiol Imaging 2005;15:69-72
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Grover S B, Singh P, Venkatachalam V P, Hekha N. Mesiodens presenting as a dentigerous cyst : Case report. Indian J Radiol Imaging [serial online] 2005 [cited 2019 Aug 22 ];15:69-72
Available from: http://www.ijri.org/text.asp?2005/15/1/69/28749
Dentigerous cysts are usually associated with unerupted teeth of the permanent dentition. When observed with erupted and complete dentition the diagnosis is a surprise. Dentigerous cyst is a developmental odontogenic cyst which originates through alterations of the reduced enamel epithelium in an unerupted tooth after the crown has been fully formed. About 95% of dentigerous cysts involve the permanent dentition and only 5% are associated with supernumerary teeth. The usual age of clinical presentation of dentigerous cyst due to supernumerary tooth is in the first 4 decades . Mesiodens is a supernumerary tooth situated between the maxillary central incisors . We report a rare case of upper labial and hard palate swelling due to a dentigerous cyst associated with a mesiodens in an elderly patient.
A 53 year old male presented with a progressively enlarging central labial swelling which was gradually increasing in size for the last five years. Clinical examination revealed a soft swelling fixed to the alveolar process of maxilla. Routine laboratory parameters were normal. Skull radiographs in postero-anterior and lateral views revealed a well marginated, midline, loculated, radiolucent lesion in the alveolar process of maxilla. The lesion which was superior to the central incisors measured 3.5 x 2cm.
A supernumerary tooth was observed to be lying vertically within the lesion, it had a cone shaped crown and a short root. Erosion of the inferior margin of maxilla along with resorption of roots of both central incisors was seen [Figure 1][Figure 2]. These radiographic appearances suggested a diagnosis of mesiodens causing dentigerous cyst. Non-contrast and contrast CT (in axial and coronal planes) was performed for further evaluation of the contents and the extent of the lesion. The lesion in the alveolar process of maxilla was found to be non-enhancing and multilocular. The contents were of fluid attenuation and showed the supernumerary tooth [Figure 3][Figure 4]. Erosion of the inferior alveolar margin was observed on bone window, which revealed an additional supernumerary tooth lying horizontally along the palatal surface of left incisors [Figure 5]. Surgical resection and histopathological examination confirmed the diagnosis of mesiodens causing dentigerous cyst. The patient remained in follow up for six months and no complications were observed.
Swelling of the upper lip can result from salivary tumor, regional infections inflammations and dentigerous cysts . A cystic swelling of the hard palate may be the result of different kinds of cysts: odontogenic, non odontogenic or bone cysts. In our patient a dentigerous cyst caused by mesiodens, a maxillary supernumerary tooth, was the cause of the swelling in the labial region.
The etiology of supernumerary teeth is unknown . One school of thought is of the view that they develop from a third tooth bud arising from the dental lamina near the permanent tooth bud or probably from splitting of the permanent bud itself. This view is supported by the fact that a supernumerary tooth usually closely resembles the teeth of the group to which it belongs . The most common supernumerary tooth is the 'Mesiodens' a tooth situated between the maxillary central incisors ,.
Mesiodens may usually be diagnosed because of delayed eruption of central incisors. Unilateral persistence of deciduous incisor, wide diastema or rotation of erupted permanent incisors are other common presentations. Rarely it manifests as dentigerous cyst . Mesiodens is seen as an additional tooth lying cranial to the central incisors. It may occur singly or in pairs, may be erupted or impacted. The direction of the crown of mesiodens may be normal, inverted or horizontal. Mesiodens is known to have a cone shaped crown and a short root as seen in our patient. It is a rare entity with a reported incidence of 0.15 to 1.9% and has a slight male predominance [2,4].
The radiological examination indicated for the diagnosis of supernumerary teeth, or mesiodens and their complications are: panoramic and / or periapical radiographs . In our patient a primary dental pathology was not suspected, therefore skull and paranasal sinus radiographs were obtained. In case supernumerary tooth / mesiodens is seen, their location and number should be documented by the radiologist. In addition the direction of the crown, location against dental arch, influence on adjacent teeth, resorption of adjacent roots and formation of dentigerous cyst should be carefully evaluated ,. Most mesiodens are located palatally to the permanent incisors. Only a few lie in the dental arch or labially to the permanent incisors . In our patient the location was labial. Resorption of the adjacent roots by mesiodens or its cyst is a rare complication . In our patient, resorption of the roots of both central incisors was observed.
Radiologically,sharply marginated radiolucent lesions of the maxilla and mandible may be odontogenic or non odontogenic in origin: such as radicular cyst, dentigerous cyst, keratocyst, fissural cysts, simple bone cyst, aneurysmal bone cyst, Stafne cyst or even tumorous such as ameloblastoma. Odontogenic cysts arise from tooth derivatives. Radicular / Apical cyst is the most common odontogenic cyst of the maxilla and mandible ,. Radiologically it arises from the apex of the root of a carious tooth and is bounded by a thin rim of cortical bone. A large radicular cyst may expand the cortex, cause root resorption in adjoining teeth or even extend into the maxillary sinus. The close differential diagnosis of a radicular cyst is periapical granuloma, but the lesion does not usually exceed 1.5cm in diameter . The differentiating feature of this entity is its relation to the root of a carious tooth.
Dentigerous cyst is the next common odontogenic cyst and is characteristically related to the crown of an unerupted tooth [6,7]. It usually occurs in the mandible and known to be both unilocular and multilocular and causes apical resorption of the adjacent teeth as observed in our patient. The diagnostic feature of this cyst is the presence of the unerupted tooth in its cavity .
Odontogenic keratocyst results from cystic degeneration of the enamel before the tooth is formed so that the cyst replaces the tooth. It is commonly noted in the mandible. Radiologically it is seen as a multiloculated lucent lesion with smooth or scalloped borders. The lesion shows fluid contents on CT and high signal intensity on T2 weighted MR images. The classical feature of this cyst is the absence of the related tooth.
Non odontogenic cysts are fissural cysts, simple bone cysts, aneurysmal bone cysts, stafne cysts . Fissural cysts occur in the lines of fusion of various bones and embryonic processes. They are observed in the region of incisive canal, globulomaxillary or nasolabial regions. The incisive canal cyst is in the midline located between the roots of central incisors of maxilla and is characteristically heart shaped . It may cause roots of the central incisors to be divergent . The globulomaxillary cyst is another maxillary cyst located between the lateral incisors and canine tooth. It extends towards the alveolar ridge and causes divergence of the roots of adjacent teeth. The nasolabial cyst occurs in the soft tissues of latreral aspect of the nose and upper lip. Fissural cysts are therefore diagnosed by their classical anatomical location .
Simple bone cyst is a unilocular cyst and is usually noted in the posterior aspect of the body of mandible. Radiologically, it is seen as a well defined radiolucent lesion with sclerotic margins. The margin of a simple bone cyst may be scalloped. Stafne bone cyst is usually located at angle of the mandible. It is detected incidentally and as seen as a radiolucent lesion well defined margins and minimal sclerosis [6,8]. Most aneurysmal bone cysts occur in tubular bones or in spine, only 2 % occur in the maxilla and mandible. Aneurysmal bone cyst is seen as expansible multiloculated radiolucent lesion. CT / MRI may reveal presence of blood or fluid contents in the cyst ,.
Ameloblastoma is more common in the mandible than in the maxilla. It is a uni / multilocular lucent lesion associated with cortical expansion. It has scalloped margins and causes resorption of roots of adjacent teeth. It has a tendency to penetrate the cortex of jaw and present as an extra osseous soft tissue mass ,. In our patient all other differential diagnoses of dentigerous cyst were ruled out on the basis of characteristic radiographic and CT features.
In conclusion, supernumerary teeth usually present with orthodontic problems in children and young adults. Their presentation in adults is rare. Dentigerous cysts in adults are usually due to unerupted teeth. Our report documents an unusually delayed presentation of a mesiodens as a dentigerous cyst and also highlights the relevant differential diagnoses.
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