Drakaran, you are right, but my old computer still need some power
I love the way that Pixologic developing ZBrush. Amazing tool.
RockyM, I made the teeth in 3D Studio Max, as well as my base mesh. So first of all, I made the body of the t-rex, modified it’s major shapes in ZBrush, and at the lovest subdivision level I exported it to the Max. I made the teeth in Max, and imported to ZBrush as subtool. After that, I made the sculpting work on them. I hope, it could help you. If you have any kinda questions, please let me know, but I’m not a great expert at sculpting, still learning.