Differential Diagnosis of Apical Periodontitis and Nasopalatine Duct Cyst

Introduction: An accurate differential diagnosis of apical periodontitis (AP) and nasopalatine duct cyst (NPDC) should be established to define the best treatment for endodontically treated maxillary anterior teeth with apical periodontitis. Three-dimensional cone beam computed tomography (CBCT) images help to plan treatment and to define an initial diagnostic hypothesis. However, endodontic treatment or retreatment may be unnecessarily prescribed when radiographs show a superimposition of the incisor foramen over the apex of maxillary central incisors, mimicking AP. Diseases of nonendodontic origin that affect the tooth apex, such as NPDC, should be included in the differential diagnosis. Methods and Results: Four clinical cases of patients with large periapical radiolucencies and similar radiographic features are described. AP is usually a consequence of endodontic infection; in cases of NPDC, however, spontaneous epithelial proliferation, in addition to bacterial infection and trauma, may also contribute to cyst formation. The frequency and recurrence rates of NPDC are low, and its behavior is less aggressive. Surgical enucleation of the periapical lesion is recommended after nonsurgical treatment does not heal AP. Conclusions: The use of new diagnostic tools, such as CBCT imaging, may provide detailed high-resolution images of oral structures, which help to make an initial diagnostic hypothesis and to plan surgery. Histopathology is mandatory for the differential diagnosis. (J Endod 2011;37:403-410)