1
general::
Also, dead and gone. Long forgotten, no longer in use, as in That argument is dead and buried, or No point in worrying about regulations that are long dead and gone. This figurative use of "having died" is usually applied to some issue. [Late 1800s]
American Heritage Idioms
2
general::
Phrase(s): dead and buried
1. Lit. dead and interred, and soon to be forgotten. • Now that Uncle Bill is dead and buried, we can read his will. 2. Fig. gone forever. • That kind of old-fashioned thinking is dead and buried.
McGrawhill's American Idioms And Phrasal Verbs