I too developed lichen planus a decade or so ago and was also declared allergic to mercury and amalgam itself. Not to nickel as far as I can remember. Replacing the fillings had no effect on the lichen planus on the left side of my tongue and after a couple of years I was finally biopsied and found to have SCC. This was in 2007. I think I was told that either I was one of the very few whose lichen planus turned nasty OR it had never been lichen planus. (However, in the pathology report from my recent recurrance surgery a lichenoid reaction was found in some of the tissue.)

I have written my story in my blog.

I would be very cautious about attributing my cancer to my amalgam fillings. There doesn't appear to be any scientific evidence. My bitterness if any is caused by the failure of an oral surgeon to biopsy me when I went to him with a very sore localised patch of lichen planus. An oral medicine specialist I later visited (an old man) said that he tells people to biopsy all patients with lichen planus like mine - just to make sure.

On the other hand, like many of my generation of New Zealanders I had a mouthful of amalgam fillings. Maybe I was more sensitive than most? I started to have mouth inflammation problems in my 30s.