Can a dental X-ray (panoramic) detect oral cancer?

Only partly. A panoramic X-ray can show cancer that has invaded or spread into the jawbone as a change in density, but early cancer in soft tissue such as the tongue, cheek lining, or palate does not appear on an X-ray. That is why oral cancer screening relies first on 1) visual inspection of the mucosa and 2) palpation for lumps, then 3) a biopsy to confirm a suspicious area, with 4) CT or MRI used to assess how far it extends. Even if the X-ray is normal, you must be examined directly if you have an ulcer or lump that has not healed in 2 weeks.