Okay so this sounds a lot like me. Be diligent. I had an irritated tongue for a LONG TIME, I had it biopsied to no avail. Still suffering I was sent to a second ENT, he looked at it and said lichen planus, but wanted to biopsy a certain area. Sure enough it was cancer. If it still hasn't healed keep at it. There is no cure for lichen planus, though it is stress related apparently - The best thing to do is see someone every three months or so. Particularly if you still have a tongue leison that shows no sign of healing. To me that is a BIG RED FLAG. best of luck - PS my first ENT said the same thing about sharp teeth, had mine filed down was tested for allergies etc... before going to someone else for a biopsy.