I'm thinking it has something to do with shadow samples settings, which I just recently changed to a proper value to match shadow blur radius (i.e. If blur is 0.4, set samples to 40 or thereabouts)... I just tried to reproduce the artifacts in the mouth and I'm not getting them any more. Prior I had my sample settings way too low. Another example of Poser inexperience. Need to do some more testing but I've got to go to work, I'll post an update of my tests later tonight.