What type of image distortion in the vertical plane causes structures to appear stretched and the apex may be invisible?

• A. Elongation
• B. Magnification
• C. Foreshortening
• D. Distortion

Answer: (A)

The main idea is vertical angulation. When the X-ray beam is not angled enough relative to the tooth’s long axis, the image stretches vertically, so the tooth appears longer than it really is—this is elongation. Because the projection can push the apex toward the film edge, the apex may become invisible. This differs from foreshortening, which happens when the beam is angled too steeply and makes structures look shorter with the apex often obscured in a different way. Magnification relates to distance and isn’t the specific vertical-plane elongation described here.