I think I'll just use a shortcut to fix the inside of the mouth. Just before render time I'll put in a bit of geometry with a black shader attached.
Also, in the previous renders the inside of the mouth appeared very bright. This was due to the 'Rim Light' not having shadows enabled. A note on that, if you don't have shadows enabled on a light, they have a tendancy to shine through geometry, annoying.
Posted by Jon Stewart