I am sorry your sister is having so many dental problems due to scleroderma. I have had a ton of dental problems including gum diseases and many teeth lost. Several times I've had to go without my partial for weeks on end, waiting for gum inflammation or mouth sores to settle down. I do know how embarrassing it is -- especially since I am missing nearly all of my upper teeth.
I've found that stressing out about it doesn't help, either, because stress increases inflammation. So I joke about it a lot, like calling myself the Toothless Wonder of the Western World. Of course, it's okay if *I* call myself names, but not so much if others do.
With scleroderma, I have personally shied away entirely from bridges or implants. It is much more practical -- and a zillion times cheaper!! -- to get partials and dentures. I love my partial because they can just keep adding teeth to it as need be. And your sister will likely be a fine candidate for a partial when the gums settle down.
Meanwhile she should of course make every effort to eliminate anything that might be worsening the inflammation, and remember to also suspect toothpaste and mouth washes. The more "natural" the better right now, if the dentist approves, such as baking soda for toothpaste and light salt water rinses instead of mouthwash because the slightest thing can make a bad situation worse or prevent the natural course of healing.
On the positive side, gums tend to heal very quickly, given the opportunity. So try to reassure her that she is not alone, and that you know someone who has happily braved the public jeers as the Toothless Wonder of the Western World, and that overall, people are quite kind and understanding, especially if you remember to give the world a great big, toothless grin! Its the frowns or pouting or tears over it that people really don't like.
One of the greeters at our local restaurant has fully half his teeth missing -- and has for years -- yet he still smiles as broad as the grand canyon, to the delight of virtually everyone.
Keep us posted on how your sister is getting on, will you? And don't give up hope. Her gums are very likely to improve, and she will totally love her new partials when the time comes. And, I still often have to go without my partial due to mouth sores, only popping them in to talk on the phone or make a public foray, or to let a pulled tooth heal. It helps to use the "bad hair day" attitude. None of us always look perfect, and often we are even at our most lovable when we look our worst, because we are more human and down to earth then.
I'm sending some extra warm hugs for you and your sister.