CC
A 52-year-old male is referred by his general dentist for evaluation of a periapical radiolucency associated with the left mandibular second molar, a new finding compared with features on a radiograph taken 1 year earlier.
Periapical cyst
Periapical cysts (also called radicular or apical cysts ) are the most common jaw cysts. They develop secondary to the inflammatory process associated with a nonvital tooth and are more common after the third decade of life.
HPI
The patient provides the antecedent history of having “longstanding pain” in the left posterior mandible, which led to the discovery of recurrent carious lesions under the existing restorations of teeth #18 and #19, approximately 2 years before the current presentation. The referral note indicates the left first molar required replacement of an existing amalgam restoration, and the left mandibular second molar required endodontic treatment. (Periapical cysts are associated with pulpal necrosis secondary to either caries or trauma.) Treatment was completed, and the teeth have remained asymptomatic for the past 2 years. A panoramic radiograph obtained 1 year ago showed no evidence of disease. The patient denies any history of swelling or purulence in the region. (Periapical cysts seldom present with any clinical symptoms, but infected cysts can present with a draining fistula.)
PMHX/PDHX/medications/allergies/SH/FH
Noncontributory
Examination
Maxillofacial. There is no discernible facial asymmetry or swelling. (Periapical cysts are rarely associated with any cortical expansion.) Facial skin overlying the region is smooth without erythema.
Neck. No cervical or submandibular lymphadenopathy can be detected. (Positive node findings could be indicative of an infectious or neoplastic process.)
Intraoral. The left mandibular first molar is restored with amalgam, and the left mandibular second molar is restored with a crown; neither tooth is mobile or tender. There is no gingival swelling or palpation tenderness along the buccal or lingual cortices.
Imaging
A panoramic radiograph is the initial study of choice for any intraosseous lesion because it provides an excellent overview of the bony anatomy, symmetry, and architecture of the maxilla and mandible and demonstrates the relationship to adjacent anatomic structures. A periapical radiograph can be obtained for small lesions, providing a more detailed outline of the borders and trabecular pattern. More extensive imaging, such as computed tomography scanning, is seldom required for management of a periapical cyst unless the diagnosis is in question.
In this patient, the recently obtained panoramic radiograph demonstrated a well-circumscribed, partially corticated radiolucent lesion associated with the left mandibular second molar mesial root partially involving the left mandibular first molar distal root ( Fig. 4.1 ). The lesion is approximately 1.5 cm in diameter. (Periapical cysts are generally between 0.5 and 1.5 cm in diameter but may enlarge to fill an entire quadrant.) There is no associated root resorption. (Although root resorption is uncommon in association with a periapical cyst, it can be seen, especially with larger cysts.). However, the periodontal ligament of the second molar mesial root is widened. (Accuracy for cold testing of the pulp in presence of prosthetic crown is estimated at 87%. Pulp testing is essential, but results should be considered in combination and context with radiology and other clinical signs and symptoms.)
Labs
No routine laboratory tests are indicated for the workup of a periapical cyst unless dictated by the medical history.
Differential diagnosis
The differential diagnosis of a periapical radiolucent lesion is greatly influenced by the clinical history and vitality of the associated tooth. If the associated tooth is nonvital and there is radiographic evidence of pulpal pathology, an inflammatory-type odontogenic etiology (periapical cyst or periapical granuloma) is the most likely diagnosis. However, a diagnosis based on histopathologic examination is warranted because developmental odontogenic cysts, developing fibro-osseous lesions, odontogenic tumors, squamous cell carcinoma, and deposits of metastatic disease, among other entities, may also occur in a periapical location. The differential diagnosis is outlined in Box 4.1 .
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Periapical granuloma —This lesion is radiographically indistinguishable from a periapical cyst and is treated in the same manner. Differentiation between periapical granulomas and a cyst has no clinical implication and is discussed below.
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Residual cyst —This is a lesion that remains after the extraction of a tooth or completion of endodontic treatment. It is radiographically and histologically identical to a periapical cyst.
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Cemento-osseous dysplasias (early) —The spectrum of lesions including focal, periapical, and florid cementoosseous dysplasia can be observed in the periapical region of teeth and are most commonly seen in middle-aged adult females of African descent. With serial observation, these lesions will progress to mixed radiolucent-radiopaque lesions and eventually to radiopaque lesions. Associated teeth are asymptomatic and vital.
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Idiopathic bone cavity (simple bone cyst, traumatic bone cyst) —Most often seen in the body of the mandible of young adults, this lesion lacks an epithelial lining and has the potential for expansion. Radiographically, it is a well-demarcated radiolucent lesion that can scallop between teeth without resorption. Associated teeth are asymptomatic and vital.
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Lingual salivary gland depressions (Stafne defect) —This well-circumscribed radiolucent lesion is most commonly seen in the posterior mandible inferior to the mandibular canal of male patients and represents a developmental concavity of the lingual cortex containing normal salivary gland tissue. Teeth near this lesion are, of course, asymptomatic and vital because the radiolucency is in fact superimposed in the periapical location.
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Other lesions —Neural lesions (schwannoma, neurofibroma) could present in a periapical location but are usually associated with the mandibular canal. Other cysts and tumors, including the lateral periodontal cysts, ameloblastomas, odontogenic keratocysts, central giant cell tumors, intraosseous mucoepidermoid carcinomas, and metastatic disease, could present in a periapical location and should be investigated. For these lesions, the associated tooth is usually vital unless there is prior endodontic therapy or concomitant pathological processes.
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