[thedoc (OP)]

Mary asked the Naked Scientists:
   
Why hasn't science figured out how to grow teeth outside of the human body yet?  If we could grow teeth outside of any animals body, then we could grow ivory tusks in a lab environment.  Then we would have a mass produced ivory product and the elephant population of the world could recover their numbers on their own.  So, what exactly is stopping science from being able to grow teeth, and ivory in a lab?

What do you think?