Hi Linda -
My husband has had lichen planus and leukoplakia for decades. His turned to SCC back in 2002 and 3 more times after that. Small lesions all removed via surgery. My husband also had the "back test" and it showed reactions to some of the metals used in fillings (and crowns?), so he too had all his metal crowns removed and replaced with porcelain. If I remember, his allergies were to the same metals as yours, although I think Brian once said most people have reactions to those metals.
My husband was prescribed a mouthwash too (unfortunately, I don't remember what it was) but it may have contained alcohol so his doctor at Shands discontinued that and prescribed another, which seems to "calm" his mouth - that is "Chlorhexidine Gluconate Oral Rinse".
My husband just had his quarterly check-up up at Shands and I asked the doctor directly, IF the lichen planus/leukoplakia caused the cancer - I got a long explanation but I don't think even he knows really if there was a direct connection. I know he called them "lichenoids" (or something). None of will ever know for sure, probably.
I can't help you with the tongue issue, because none of my husband's cancers were on his tongue, but we can identify with the "metal in the mouth" questions. If I were you, I'd do a search in OCF over "metal fillings", "amalgams", etc. and you will read tons of information on this subject. Best of best wishes for your surgery next week. Keep us updated, and don't hesitate to ask us questions about our OC processes.
Warmly, JaneP