A 36-year-old male visited a dentist for a routine checkup. Radiographic examination revealed a lesion in the mandibular third molar area.
Joen Iannucci Haring, DDS, MS
History
When questioned abut the lesion in the mandibular molar region, the patient denied any history of signs or symptoms associated with this region. The patient also denied any history of trauma to the involved area. The patient appeared to be in a generally good state of health, with no significant past medical history. The patient`s dental history included regular dental examinations and routine dental treatment. At the time of the dental appointment, the patient was not taking medications of any kind.
Examinations
The patient`s vital signs were all found to be within normal limits. Examination of the head and neck region revealed no enlarged or palpable lymph nodes. Examination of the soft tissues of the oral cavity revealed no unusual findings. No bony abnormalities were noted.
Radiographic examination revealed a large, unilocular radiolucent lesion around the crown of impacted tooth #17 (see radiograph). The periphery of the radiolucent lesion appeared smooth and corticated. No other abnormalities were noted on the remaining films in the complete series.
Clinical diagnosis
Based on the clinical information and unilocular radiolucent appearance of the lesion, which one of the following is the most likely diagnosis?
* ameloblastoma
* dentigerous cyst
* odontogenic keratocyst
* adenomatoid odontogenic tumor
* ameloblastic fibro-odontoma
Diagnosis
dentigerous cyst
Discussion
The dentigerous cyst (a.k.a. follicular cyst) is the most common developmental odontogenic cyst. This lesion is seen in association with the crown of an unerupted or impacted tooth. The term dentigerous means containing or bearing teeth. This lesion, by definition, contains the crown of a tooth. The dentigerous cyst results from the separation of the dental follicle from the crown of an unerupted tooth. The pathogenesis of the dentigerous cyst is unknown.
Clinical features
The dentigerous cyst is most often seen in association with the teeth that are most often impacted - the third molars and the canines. Almost 50 percent of dentigerous cysts develop around mandibular third molars. The dentigerous cyst is almost always seen in association with a permanent tooth. Rarely is a deciduous tooth affected. The dentigerous cyst most often occurs during the second and third decades; males are affected more frequently than females.
The dentigerous cyst is usually painless. Delayed eruption of a tooth may be the only sign of a problem. Occasionally pain, expansion, displacement of teeth, and root resorption may occur. In cases of expansion, a firm swelling in the area of the missing tooth may be clinically apparent. In some cases, dentigerous cysts may exhibit great growth potential and extend to include the entire ramus of the mandible. These large lesions may cause a marked facial asymmetry and predispose the bone to pathologic fracture.
Radiographic features
Most dentigerous cysts are discovered during routine radiographic examination. The dentigerous cyst appears as a well-defined, unilocular radiolucency that surrounds the crown of an impacted tooth. The dentigerous cyst is not a multiocular lesion. The dentigerous cyst may range in size from less than 2 centimeters in diameter to a large and expansile lesion. The borders of the dentigerous cyst appear smooth and corticated on a radiograph. When viewed on a radiograph, the dentigerous cyst may be seen in association with displacement of adjacent teeth, root resorption, and displacement of the mandibular canal. The diagnosis of a dentigerous cyst cannot be made from a radiograph alone.
Diagnosis
The diagnosis of a dentigerous cyst is based on histologic examination. Other lesions to include in the differential diagnosis are the ameloblastoma and odontogenic keratocyst.
Treatment
The dentigerous cyst requires surgical removal. If the dentigerous cyst is left untreated, it will continue to grow. It may result in extensive bone loss, displacement of teeth, root resorption, and pathologic fracture. The surgical procedure required is dictated by the size of the lesion. Removal of the associated tooth is the treatment of choice for small lesions. Large and extensive lesions, if removed surgically, may result in a fractured jaw. Larger dentigerous cysts are often treated using marsupialization. The dentigerous cyst rarely recurs following treatment. The prognosis is excellent.
Joen Iannucci Haring, DDS, MS, is an associate professor of clinical dentistry, Section of Primary Care, The Ohio State University College of Dentistry.
