On a dental radiograph, the inverted Y is formed by the floor of the nasal fossa and which other structure?

• A. The posterior border of the maxillary sinus.
• B. The zygomatic arch.
• C. The inferior nasal concha.
• D. The anterior border of the maxillary sinus.

Answer: (D)

The inverted Y on a dental radiograph marks the boundary between the nasal cavity and the maxillary sinus, formed where the floor of the nasal fossa meets the anterior border of the maxillary sinus. This intersection creates the recognizable Y shape and helps identify the maxillary sinus region on a radiograph. The other structures don’t form this specific junction: the posterior border of the maxillary sinus lies along a different wall, the inferior nasal concha sits inside the nasal cavity away from the sinus wall, and the zygomatic arch appears laterally but does not create the Y with the nasal floor.