Which dental structures appear gray on a radiograph?

• A. Dentin, which absorbs and transmits x-rays somewhere in between.
• B. Enamel
• C. Lamina dura
• D. Pulp

Answer: (C)

On radiographs, density governs brightness: enamel is highly radiopaque (white), dentin is less dense and appears as gray, and the pulp is radiolucent (dark). The lamina dura is the dense cortical bone lining the tooth socket, shown as a thin, continuous radiopaque border around the root. This distinct border often appears as a gray-to-white line that clearly outlines the root against the surrounding bone, making it the structure most associated with a gray appearance on standard bitewing or periapical radiographs. Its presence and continuity are key for evaluating tooth stability and periodontal health.