Definition: A cyst that develops around the crown of an unerupted tooth, most commonly associated with third molars and maxillary canines.
Radiographic Features:
- Location: Surrounding the crown of an unerupted tooth
- Edge: Well-defined, corticated
- Shape: Round to ovoid
- Internal structure: Radiolucent, unilocular
- Other:
- Cyst border continuous with cemento-enamel junction of unerupted tooth
- May displace associated tooth apically
- Can displace or resorb adjacent teeth as it enlarges
- Number: Typically single, rarely multiple
Key points:
- Differentiate from hyperplastic follicle:
- Hyperplastic follicle: <5 mm space between enamel and lesion edge
- Dentigerous cyst: >5 mm space between enamel and lesion edge
- Second most common odontogenic cyst after radicular cyst
- Can grow to considerable size if left untreated
Clinical significance:
- May prevent tooth eruption
- Risk of pathological fracture if large
- Potential for ameloblastoma or epidermoid carcinoma development (rare)
- Treatment usually involves enucleation and removal of associated tooth
Note: Careful measurement of the space between the tooth crown and cyst border is crucial for accurate diagnosis and differentiation from a hyperplastic follicle.