Uv rays contribute to skin aging. how about x-rays? they are ionizing, so do xr/ct/cbct scans contribute significantly to skin aging as well?

They can: Yes prolonged exposure to ionizing radiation may lead to increased free radical formation, aging and mutation.

Not reasonable: Although dental x-rays are ionizing radiation, the dosage is so low for a single film that it isn't significant. A full series of films, or cone beam ct, or panoramic x-ray is about the equivalent of living in denver co for about a week. Or flying to paris. So unless this is repeated on such an exaggerated frequency, the dosage is insignificant. Especially with digital high speed x-rays.