Final answer:
Metallic artifacts on CBCT images cause beam hardening artifacts, leading to decreased image contrast, not increased image sharpness or improved spatial resolution.
Step-by-step explanation:
On CBCT images, metallic artifacts cause beam hardening artifacts. These artifacts occur because metal has a high atomic number, which results in it absorbing more X-rays than the surrounding tissue.
This differential absorption creates streaks and dark bands on the reconstructed image, leading to decreased image contrast and reduced diagnostic value. It does not lead to increased image sharpness or improved spatial resolution.