Blender is not a gaming engine its a Open-source 3d modeling software, with a render engine and with practice you can develope the teeth your looking for in your project, it will just take you some time on how to learn to do it if your new to blender

and if you need a gaming engine you can get Cryengine3 as a free demo and is a Gaming engine software.  but it is not modeling software so you can not develop  models with it.  http://cryengine-3.en.softonic.com/

I think  for what your needs are I would suggest using  3D MAX or zbrush which are not free and have a very steep learning curve on  learning how to use it.

I have not seen any free teeth models anywhere but you can find teeth morphs & sets here at rendo http://www.renderosity.com/mod/bcs/search.php?criteria=teeth&adv_search=  

and at daz3d.com  http://www.daz3d.com/catalogsearch/result/?q=teeth&x=0&y=0

Good Luck :)