In the meantime, persuading her to floss, use interdontal brushes and also a good maouthwash can only help. Colgate do some blue n white plastic interdontal brushes which are very gentle, nicer to use than the wire-middled-sort. The routine of (obsessively) flossing and between-cleaning will inevitably help delay gum disease, and it's not too late now.
Oh, and defintiely an electronic toothbrush. Definitely.
And if she can do this, she'll hopefully get to the point where it doesn't hurt so much to have a 'major de-coke'.
Best of luck.