Which statement about white areas on radiographs is true?

• A. Pulp and PDL absorb more x-rays.
• B. Dentin absorbs and transmits x-rays somewhere in between.
• C. Enamel and lamina dura absorb more x-rays.
• D. Cortical bone absorbs less.

Answer: (C)

White areas on radiographs correspond to structures that absorb more X-rays because they are highly mineralized or dense. Enamel is the most mineralized dental tissue, so it shows up very white. The lamina dura, the dense bony line around the tooth socket, is also highly radiopaque. So a statement that enamel and lamina dura absorb more X-rays and appear white is true. In contrast, pulp and the periodontal ligament are soft tissues and appear darker (radiolucent), and while cortical bone is also dense and radiopaque, saying it absorbs less would be incorrect. Dentin sits between enamel and pulp in radiodensity, not as white as enamel.