Which term best describes a dark area on a tooth X-ray caused by high transmission of X-rays?

• A. Radiolucency
• B. Radiopacity
• C. Opacity
• D. Luminosity

Answer: (A)

In dental radiography, dark areas show where X-rays pass through with little attenuation because the tissue is less dense. This is described as radiolucency. Radiopacity refers to bright areas where dense structures like enamel or bone block more X-rays. Opacity and luminosity aren’t standard terms used to describe dental radiographs in this context. So the dark, high-transmission area is radiolucency. For example, a carious lesion or the pulp chamber can appear radiolucent since those areas have less mineral content and attenuate fewer X-rays.