What is the White Cylindracal Exposed Area That I See in my Root Canal?

Had root canal re-done.. there is "a 2nd root" (tooth next to canine tooth)... I am still, and again, in the medicated and temporary filling stage, but I have an aweful taste in mouth. When looking at the root canal tooth (I see a white cylindrical center with a pink outer surrounding. Is the white area the medication and if so, should it be exposed and is that what I'm tasting??? When I apply my tongue to the biting surface of that tooth, I get a taste that seems to stay in my whole mouth.