To get the type of resolutions you will need for a dental crown you will need a Stereolithograpy 3d printer. They basically use light to cure resin. The B2 uses a projector, the Form 1, a laser. I ran across a new printer from dwslab.com. You might want to check that out too. I have also seen specific resins that will burn out cleanly. A lot of jewelers are designing jewelry in a CAD program like Rhino, then printing out a pattern and investing it just like the traditional lost wax process. That being said, I am not sure if any of those printers have the resolution you will require to have an accurately fitting crown.