Sameer Puri D.D.S. Don't have undercuts on your margins. This is an extreme example but if you have an undercut on your prep, the machine will try to mill it. This becomes especially critical in inlay/onlay type preparations. The best thing you can do is prep smooth clean walls that draw with no undercuts what so ever.
Check out what happens when you have an undercut. I took this stone model to show you what happens. The machine will try to mill an undercut so don't prep with one!
