Fig. 4.

CBCT images show the four shapes of the nasopalatine canal as seen on sagittal planes based on the labial and palatal walls of the nasopalatine canal. A. A cylindrical shape formed by parallel labial and palatal walls of the nasopalatine canal. B. A funnel shape formed by an increasing antero-posterior dimension of the nasopalatine canal from the nasal fossa to the hard palate. C. An hourglass shape in which the narrowest antero-posterior dimension of the NPC was at the mid-level compared to the dimensions at the nasal fossa and hard palate levels. D. A spindle shape in which the widest antero-posterior dimension of the nasopalatine canal was at the mid-level compared to the dimensions at the nasal fossa and hard palate levels.