Oh, Johanna, so sorry to hear that there is no definite plan of action for dear Binx. In the case of rareness, my parent's Great Pyr has a rare cancer and his treatment is also a guess. His specialist contacted all the vet schools and vet specialists to get their opinions. They are trying an herbal (rutin) and diuretic protocol on him. It is hit or miss. So far, so good.
They may not know how to attack his problem yet. I'd go with the human dentist or vet school. Good luck and know that both of you are in our thoughts always.