Ct scan for fullness,tinnitus in both ears.there is a chronically appearing opacified right mastoid air cell.no sigmoid plate dehiscence.there is osteoneogenesis and opacification of the air cell.no adjacent osseous erosion. left is clear. meaning?

The opacification is probably a residua of an old middle ear infection & associated mastoid inflammation. The enlarged mastoid bone is another effect of the old mastoiditis. You don't mention what symptoms you're experiencing. I don't think there's an active inflammatory process going on by CT scan, but your ENT, who knows your story, is best to advise you.