Patent nasopalatine duct: a diagnostic pitfall.

We describe a patient in whom the combination of excessive air in the maxillary sinus and the presence of a patent nasopalatine duct led to misdiagnosis and subsequent treatment of a non-existent oroantral perforation. When a radiograph indicates that antral involvement during removal of a maxillary molar is unlikely, and yet a routine postoperative nose-blowing test contradicts this, the possible presence of a pre-existent oronasal communication such as a patent nasopalatine duct should be considered.