how to make a single surface and then a single solid part out of too many sveral connected surfaces in SolidWorks?

I have imported a dxf format of human skull in SolidWorks and what I see on each part ( teeth) different bones in skull is the geometry of those bones/teeth made out of so many small surfaces connected to each other. I will have to make assemblies between mandible and lower teeth and upper jaw and upper teeth. How can I change each tooth or bone to only one solid part with one surface? In another world how can I connect these surfaces together to make one single surface? How can I make one solid out of that surface?I have attached a single tooth here.