Akkadian

dūr šinni - gums (CAD D 197, AHw. 155)

may go back to PS *dVrdVr-, being reinterpreted as dūru ‘walľ by popular etymology (Kogan 2003a:128–129).

PS
*dVrdVr- - toothless mouth, gum (SED I No. 56; Kogan 2011: 222)