I have a Pom, he's only 1 and so far no teeth problems. However, Pom's are known to have bad teeth.
I haven't heard of dental disease causing protein in the kidneys? Will a cleaning solve the dental disease?
We have another member who has Pom's. She had one that had kidney problems along with stones. If I remember right, her vet thought the stones were related to the food prescribed for the kidney problems.
My experience has been that the cause of protein in the urine is difficult to solve. I also have a mix, I think chow/border collie named Charlie that has kidney and urine issues. He has always had diluted urine and this spring it was showing elevated levels of protein as well. The vet said it could be anything from diet to kidney disease. We did a urine protein creatinine ratio, that ruled out Kidney disease and then were doing blood tests which kept coming back borderline low to normal. Charlie has always acted completely fine, has always had diluted urine, and then my vet became ill with cancer, so we still haven't figured out what is going on, if anything.
I wish you luck and hope you find out what is going on with Autumn. Please let us know how things progress!!