Re: Tried everything but can't seem to get rid of coated tongue.

Thick coat in back of tongue may mean toxic GI tract - teeth impressions are related to weakening muscles due to poor absorption. Your duodenum/small intestine (absorption area) maybe be coated with junk.
You may want to look at cleaning the small bowel with okra pepsin E3 or gastrex from standard process or simply taking okra for a while. As mentioned, TCM has a different perspective on tongue diagnosis and there may be herbs that will clear and blockages or excess dampness.
Mike