It seems like some of the new models are having trouble with the misalignment of their teeth. To temporarily fix that (until I find a way to correct the morphs and re-upload them), I have two solutions:
Go to "Control & Physics 1" and click on "Reset Pose."
Download this fix: Teeth Fix and follow the instructions in the post.
You'll need to do this in every scene, but as I mentioned, this is just a temporary solution. I apologize for any inconvenience this may have caused you.