Large Dentigerous Cyst

Transcription

1 Volume Feb 2016 This Lecture Series qualifies for 0.5 Informal CPD Learning Hours Large Dentigerous Cyst By Dr Hassem Geha A 55 year-old male presented with a painless swelling in the right mandible. His extraoral examination showed a mild asymmetry between the right and left sides. His intraoral examination revealed some missing teeth and many restorations. There was a mild swelling in the left mandibular 3rd molar area and the mucosa was slightly of red colour. In the right mandible there was a tender swelling extending from the area of 46 to level of the area of 48 with normal gingiva and mucosa texture. There was no sign of exudate at the level of the gingiva in this area. Teeth 47 and 48 were vital. A panoramic radiograph was acquired followed by a cone beam CT of the maxillo-facial compels. In the right mandible tooth 48 was impacted in a horizontal position. There is a well-defined corticated radiolucency apparently originating at the CEJ level of 48 and extending anteriorly and at the level of the apices of 47 and 46 to the area of missing 45, inferiorly to the level of the mandibular cortex. In its posterior segments, the radiolucency extends to the level of the alveolar crest superiorly and to the level of the mandibular canal at the mid-level of the ramus along the distal root of 48.

2 The radiolucency extends also to the level of the mandibular angle inferior to the mesial aspect of the crown of this tooth. The buccal and lingual cortical plates are thinned and expanded with no radiographing signs of perforation. The inferior cortex and the alveolar crest where the lesion extends appear slightly expanding with no radiographic signs of perforation too. Tooth 48 is displaced posteriorly with its roots displaced lingual relative to the mandibular canal.the mandibular canal is displaced inferiorly and into the buccal cortex. The apices of the roots of 47 and 46 are mildly resorbed. In the left mandible tooth 38 is impacted in a mesioversion with its crown at proximity of the distal aspect of the CEJ of 37 and causing caries in that area. There is a distocoronal radiolucency where the adjacent trabecular bone appears to be of increased density. The roots of 38 are buccal relative to the left mandibular canal. In the right maxilla there is a small well defined corticated radio -lucency superimposing over the distal aspect of the root Based on the age and location of the lesion in the right mandible, findings in the right mandible are suggestive of a being a slow growing odontogenic lesion, most likely originating around 48. The lesion has a mixed behaviour including: This lesion is likely to be a dentigerous cyst taking into account its size relative to the age of the patient. These cysts usually develop at the age of 30 and can reach large sizes if left untreated. They can also cause root resoprtion if they were in contact with the teeth for a long period of time. If left untreated some dentigerous cysts can become either keratocystic odontogenic tumors (KOT) or mural ameloblastomas. In this case the distinction is not clear. With the presence of the radiolucency noted distal to 15 that can be a KOT or a lateral periodontal cyst, the likelihood of the large mandibular lesion of being a KOT also increases. For impacted 38 there is a highly likelihood of pericoronitis and reactive ostesclerosis. This needs to be addressed to avoid any spread of the possible infection to the retromolar area. Prior to any further exam an aspiration of the lesion is advised to evaluate the content of this lesion. Usually a dentigerous cyst will show some clear fluid and KOT will give out a cheesy yellowish colour, while the ameloblastoma will yield some blood. image 1 A cystic behaviour supported by the well-defined and corticated border as well as mild expansion of the cortical plates A tumoral behaviour suggested by the root resorption, the tooth displacement and also the expansion The patient underwent surgical removal of teeth 48, 47 and 47 and enucleation of the lesion in the right mandible. About 16 days later, clinical healing appeared to be progressing well and the patient will be re-evaluated in six months time with a new OPG to monitor bony infilling. The histopathology was in keeping with a dentigerous cyst.

3 image 2 Cross Sectional views of the right mandible showing the expansion of the cortical plates and the displacement of the mandibular canal image 3 image 4 Cropped panoramic reconstruction with tracing of the mandibular canal Sagittal view of the right mandible showing the location of 48

4 PATHOLOGY A dentigerous cyst is formed by the hydrostatic force exerted by the accumulation of fluid between reduced enamel epithelium and the tooth crown of unerupted teeth. As such the cyst encloses the crown and is attached at the neck at the cemento-enamel junction 5. They almost exclusively occur in permanent dentition. The cyst is lined by stratified squamous nonkeratinising epithelium. Over 75% of all cases are located in the mandible, with the most commonly involved teeth being: Mandibular third molar (most common) Maxillary third molar (2nd most common) Maxillary canine Mandibular second premolar Axial view showing the positioning of 48 Recurrence is uncommon, but may occur if parts of the cyst lining are left in situ. EPIDEMIOLOGY COMPLICATIONS Dentigerous cysts are the second most common odontogenic cysts after those related to the roots of the teeth (periapical cysts). These types of cysts usually present in the 2nd to 4th decades of life and are uncommonly seen in childhood because they almost exclusively occur in secondary dentition. Pathological jaw fracture if large enough In rare cases dentigerous cysts may develop into a mural ameloblastoma There is a potential for development of squamous cell carcinoma in the context of chronic infection CLINICAL PRESENTATION Typically, dentigerous cysts are painless and are usually discovered during routine radiographic examination, however they may be large and result in a palpable mass. Additionally, as they grow they might displace adjacent teeth.

5 REFERENCES 1. Larheim TA, Westesson P. Maxillofacial Imaging. Springer Verlag. (2008) ISBN: Read it at Google Books - Find it at Amazon 2. Dunfee BL, Sakai O, Pistey R et-al. Radiologic and pathologic characteristics of benign and malignant lesions of the mandible. Radiographics. 26 (6): doi: /rg Pubmed citation 3. Som PM, Curtin HD. Head and neck imaging. Mosby Inc. (2003) ISBN: Read it at Google Books - Find it at Amazon 4. Han MH, Chang KH, Lee CH et-al. Cystic expansile masses of the maxilla: differential diagnosis with CT and MR. AJNR Am J Neuroradiol. 1995;16 (2): AJNR Am J Neuroradiol (abstract) - Pubmed citation 5. Becker A. The orthodontic treatment of impacted teeth. Dunitz Martin Ltd. (2007) ISBN: Read it at Google Books - Find it at Amazon 6. Barnes L. Surgical pathology of the head and neck. Marcel Dekker. (2001) ISBN: X. Read it at Google Books - Find it at Amazon 7. Som PM, Curtin HD. Head and Neck Imaging (Expert Consult). Mosby. ISBN:B005F2Z468. Read it at Google Books - Find it at Amazon NEWSLETTER WEBINAR REPORTING SERVICES To receive up to date industry information, Practice Management Tips, Equipment Reviews, Legislative updates, and Tech Tips then subscribe to our Newsletter by visiting / subscribe Do you need to keep your CPD/CPE up to date, then make sure you join our next Webinar and join in on the presentations and discussions by respected industry experts.visit to register. We welcome new clinics to PRO Dental Radiology who are not enjoying the benefits of sub-specialty reporting. info@prodentalradiology.com to find out how you can join our reporting services or call our team on