Dentigerous cysts (also called follicular cysts) are benign, non-inflammatory odontogenic cysts that are thought to be developmental in origin.
Dentigerous cysts are the second most common odontogenic cysts after those related to the roots of the teeth (periapical cysts) 3. They usually present in the 2nd to 4th decades of life and are rarely seen in childhood because they almost exclusively occur in secondary dentition 1-3.
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 1-3,5. 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 nonkeratinizing epithelium.
Over 75% of all cases are located in the mandible, with the most commonly involved teeth being 1,3:
- mandibular third molar (most common)
- maxillary third molar (2nd most common)
- maxillary canine
- mandibular second premolar
Typically, dentigerous cysts are painless and discovered during routine radiographic examination, however they may be large and result in a palpable mass. Additionally as they grow they displace adjacent teeth 2.
Several cases of dentigerous cysts presenting as recurrent head and neck infection or as a deep neck space abscess have been described.
Dentigerous cysts are frequently seen on OPGs, and often require no further imaging to make the diagnosis. CT and MRI give additional information, and help in distinguishing this entity from other cystic lesions of the mandible and maxilla.
When small, it is difficult to differentiate a dentigerous cyst from a large but normal dental follicle. A working definition is that a dentigerous cyst exists when the distance between the crown and dental sac is greater than 2.5 - 3.0mm 5-6.
Plain film (OPG)
Radiographically, dentigerous cysts appear as unilocular well defined pericoronal radiolucencies centred on an impacted or unerupted tooth. They have a thin regular sclerotic margin and expand the overlying cortex without cortical breach (unless superimposed fracture or infection). Their size is extremely variable, ranging from only slightly greater in size than a normal follicle to very large, appearing to hollow-out the majority of the jaw 1-4.
Erosion / resorption of the roots of adjacent teeth is not sometimes seen 6.
CT appearances mirror those of plain film. The relationship to the unerupted tooth can often be better appreciated, and the cyst cavity is filled with water density fluid. Maxillary lesions may project superiorly into the paranasal sinuses or nasal cavity 3-4.
The main role of MRI is help distinguish these lesions from other cystic lesions of the jaw, when appearances are atypical.
- T1 - low signal, similar to water / CSF
- T2 - high signal, similar to water / CSF
- T1 C+ (Gd) - no solid component or enhancement, except for potentially a thin peripheral rim of enhancement 1,3.
- pathological jaw fracture - if large enough
- very rarely dentigerous cysts may develop into a mural ameloblastoma 2.
- there is a potential of development of squamous cell carcinoma in the context of chronic infection
Treatment and prognosis
Treatment usually involves removal of the entire cyst and the associated unerupted tooth. In patients with very large lesion or who are unfit medically, marsupialisaiton is an option 6.
Recurrence is uncommon, but may occur if parts of the cyst lining are left in situ 6.
When small, it is difficult to differentiate a dentigerous cyst from a large but normal dental follicle 5-6.
When larger, the differential is essential that of lytic lesions of the jaw and includes:
- periapical cyst (radicular cyst)
- aneurysmal bone cyst (ABC)
- keratocystic odontic tumour (odontogenic keratocyst)
- cherubism (fibrous dysplasia)
- Stafne cyst
Lucent lesions of the jaw
- 1. Larheim TA, Westesson P. Maxillofacial Imaging. Springer Verlag. (2008) ISBN:3540786856. 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): 1751-68. doi:10.1148/rg.266055189 - Pubmed citation
- 3. Som PM, Curtin HD. Head and neck imaging. Mosby Inc. (2003) ISBN:0323009425. 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): 333-8. AJNR Am J Neuroradiol (abstract) - Pubmed citation
- 5. Becker A. The orthodontic treatment of impacted teeth. Dunitz Martin Ltd. (2007) ISBN:1841844756. Read it at Google Books - Find it at Amazon
- 6. Barnes L. Surgical pathology of the head and neck. Marcel Dekker. (2001) ISBN:082470469X. Read it at Google Books - Find it at Amazon
Synonyms & Alternative Spellings
|Synonyms or Alternative Spelling||Include in Listings?|
|Follicular cyst (dental)||✓|
|Follicular cyst of the mandible||✗|
|Follicular cyst of the maxilla||✗|