If you have carnivore skulls, these images should help you:
Side -
4.bp.blogspot.com/-haevYZ3-4-c…Front -
encrypted-tbn3.gstatic.com/ima…In the smaller premolars (not the tiny front incisors) you can look on either side of the tooth. One side will be perfectly slick, while the other side will have a groove. The groove is on the inside of the mouth while the slick side shows on the outside.
As for the tiny front teeth, always remember that the smaller ones are in the middle. When putting skulls together, I work biggest to smallest. Put in the fangs, then the little fangs next to it, then the next size down, then the final tiny ones in the middle.
With bottom teeth, you will see a little notch in the face of the tooth. That little notch always aims outward. So when putting the bottom jaw back together, I put in the lower fangs, then the biggest of the front bottoms in with that little notch pointing outward. Then just work your way to the smaller teeth.