Which term is the opposite of radiolucency?

• A. Radiolucency
• B. Radiopacity
• C. Density
• D. Contrast

Answer: (B)

On dental radiographs, how dark or light a structure appears is about how much X-ray radiation it blocks. Dense structures block more X-rays and look lighter; this light-shaded property is called radiopacity. Less dense areas block fewer X-rays and look darker, which is radiolucency. So the term that describes being more radiopaque—the opposite of radiolucent—is radiopacity. For context, enamel and bone are typically radiopaque (light on the image), while pulp chambers and carious lesions are radiolucent (dark). The other terms don’t fit as the opposites: radiolucency is simply the dark appearance, density is a general property of how strongly a structure attenuates X-rays, and contrast refers to the difference in shading between adjacent structures, not the inherent property opposite radiolucency.