Mouth looks a little too low and so it stretches the teeth.
Also the contours below the nose and above the teeth seem non-existent, I think it needs more tweaking mainly in that area.
Everything looks a little soft too imo, nose may be slightly high on the head too.
Eyes are great, especially the brow.
Cheeks are excellent too.
Teeth look a little too rectangular, they're usually a lot thinner at the bottom on a "naked" skull. What reference did you use?

Anyways, nice work ZeT, keep it up