In CBCT imaging, what do black, gray, and white densities correspond to?

• A. Black = air; Gray = dentin, marrow space, soft tissue; White = bone, enamel, restorations, metallic foreign bodies, calcifications
• B. Black = bone; Gray = air; White = enamel
• C. Black = metal; Gray = bone; White = air
• D. Black = enamel; Gray = dentin; White = soft tissue

Answer: (A)

In CBCT imaging, the grayscale reflects how much the X-ray beam is attenuated by different tissues. Air hardly attenuates the beam, so it appears black. Dentin, marrow spaces, and soft tissues attenuate more than air but less than dense minerals, so they show up in gray. Dense mineralized structures—bone and enamel—as well as restorations and metallic foreign bodies attenuate the beam the most, appearing white. This mapping matches the described pattern: black for air, gray for dentin/marrow/soft tissue, and white for bone/enamel/restorations/metal. Note that CBCT grayscale is machine-dependent and not standardized like Hounsfield units, but the relative appearance follows the same attenuation principles.