[Persistent nasopalatine duct: a diagnostic challenge].

The nasopalatine duct (DNP) originates within the nasopalatine canal from epithelial remnants and then develops into an epithelialized connection that extends from the oral cavity to the nasal cavity. Normally, the DNP closes or degenerates in humans before birth. If the DNP persists after birth, oral openings may appear bilaterally, unilaterally or centrally.