That being said, if you're trying to emulate that leering ghoul smile that Julia Roberts does I would consider adding scaling dials to the lower and upper jaw actors that work concurrent with the smile wide morph. That would be a way to more accurately portray this. If you study pictures of her you'll see that her teeth and gums are quite wide also, this would help sell the effect and mitigate the huge gaps you are left with in it's current state.