On a radiograph, where are cusp tips projected relative to the receptor?

• A. Away from the receptor
• B. Toward the receptor
• C. At the receptor plane
• D. Beyond the receptor

Answer: (B)

Radiographs are two‑dimensional projections of three‑dimensional structures. The receptor sits beyond the tooth away from the X‑ray source, so every point on the tooth is projected along the X‑ray path onto that receptor. Structures closer to the receptor are mapped onto the film with less magnification and appear nearer to the receptor plane on the image, while structures farther away are magnified more. The cusp tips are the parts of the crown closest to the receptor in this setup, so they are projected toward the receptor on the radiograph. In short, the cusp tips appear toward the receptor, while more distant parts like the apices appear farther from that plane.