Can a dentist tell if a tooth is decaying under a crown?

Yes, a dentist can often tell if a tooth is decaying under a crown, but it can be more difficult than detecting decay on an uncovered tooth because the crown covers the tooth. Dentists use several methods to check. Visually, they look for signs like gum inflammation around the crown, dark lines at the margin where crown meets tooth, or holes in the crown. They use dental X-rays, bitewing and periapical radiographs, which can show decay as dark shadows under the crown, especially at the edges, though metal crowns can block X-ray view somewhat. They use a dental explorer to feel for soft spots, gaps, or looseness at the crown margins where bacteria can enter. They may use laser fluorescence devices that detect decay. If a crown is loose, has a bad smell, or patient reports sensitivity to cold, sweets, or biting, that suggests decay underneath. Sometimes decay under a crown is hidden and only found when crown is removed or when infection shows as abscess on X-ray. Regular checkups, flossing around crowns, and X-rays every year help catch decay early. If decay is extensive, the crown may need removal, decay treatment, and new crown or extraction.