Calcifying odontogenic cyst resembling clinical signs of vertical root fracture of a maxillary canine.

BACKGROUND: Calcifying odontogenic cyst (COC) can be misdiagnosed as a lesion of endodontic origin when it is in close proximity to the periradicular tissue, and pulp sensibility tests are indispensable for differential diagnosis. However, when the adjacent teeth are necrotic or already endodontically treated, diagnosis becomes challenging. CASE DESCRIPTION: In this case report, a maxillary canine with an inadequate root canal treatment was considered as the source of an endodontic infection. Eight months after the retreatment, the patient sought treatment for a buccal intraoral swelling and a deep periodontal pocket and was referred for cone-beam computed tomography with a provisional diagnosis of a vertical root fracture. The tomography revealed an extensive lesion buccally to the roots of the canine and the adjacent vital lateral incisor. An unusual extended external resorption of the root of the vital lateral incisor was also evident. This finding shifted the diagnostic thinking toward a lesion of nonendodontic origin. The lesion was surgically enucleated, and the histopathologic examination confirmed the diagnosis of a COC. PRACTICAL IMPLICATIONS: Clinicians always must bear in mind the chance of a nonendodontic lesion masquerading as a lesion of endodontic origin. Cone-beam computed tomography should be considered in cases of doubt or in lesions refractory to endodontic treatment, as it can provide information on the clinicopathologic features of the lesion.