Background: A preponderance of periapical radiolucencies are of inflammatory etiology (radicular cysts or periapical granulomas) secondary to pulpal disease. In some instances, however, a suspected periapical inflammatory lesion is not a consequence of pulpal disease but instead represents a lesion of noninflammatory origin. The differential diagnosis for such lesions is broad, ranging from odontogenic cysts and tumors to metastatic disease. As the biological behavior of such lesions is varied, the distinction between inflammatory odontogenic periapical lesions and lesions of noninflammatory origin in a periapical location is critical.

Methods: A retrospective study of 5,993 archival periapical biopsies over a span of 15 years from the database of the Oral Pathology Biopsy Service in the Henry M. Goldman School of Dental Medicine at Boston University recorded the incidence of various lesions in a periapical location.

Results: Of the cases studied, 97.2% represented lesions of inflammatory origin with histopathologic diagnoses as follows: periapical granuloma (60.0%), radicular cyst (36.7%), periapical fibrous scar (0.27 %), and periapical abscess (0.23 %). The remaining 2.8% cases were lesions of noninflammatory origin with histopathologic diagnoses of odontogenic keratocyst (also known as keratocystic odontogenic tumor), benign fibro-osseous lesions, and ameloblastoma. One patient had Langerhans cell disease, and 1 had central giant cell granuloma.

Conclusions: Although most periapical specimens biopsied represented expected inflammatory periapical lesions, the biological behavior of underdiagnosed lesions may have considerable consequences for both the patient and the clinician.

Practical implications: This article serves to inform clinicians regarding the diversity of lesions arising in the periapical region of the jaws, to assist in the formulation of differential diagnoses, and to highlight the importance of submission of lesional tissue for histopathologic evaluation and definitive diagnosis when biopsy is clinically indicated.