This challenge took me about 2 hours. Since this is my first time to model a set of teeth, I followed a tutorial from a Character Modeling book. I also used a general picture of a set of teeth as reference guide but didn't follow it strictly.
A few months ago, I attempted to create my very first 3D model of a human hand, with realistic knuckles, fingernails, PIP and DIP joints. Looking back, I still think it could do with a couple of more improvements and editing, but it really was a good first attempt (at least for me).
Here's my take on that challenge.