It sounds like you are asking to learn the proper methods for creating surface models in SolidWorks. I suggest reviewing these presentations and videos as an introduction to SolidWorks surfacing tools.
- Introduction to Boundary Surface
- Everything Curves and Surfaces
- Surfacing, Where Do I Even Start?
- Advanced Modeling 301
You want to design a model of a 3D scan of a tooth that was probably created from a plaster mold impression. I saw a 'how stuff works' video on how they make crowns and it looks like they're machined using a 5-axis lathe directly from a positive of the mold. What part of the tooth are you trying to design.
After that, it would be useful to know what the design intent is (class-A surfaces, symmetry about an axis, manufacturability, etc.) Knowing that will make it easier to suggest methods for approaching your design.