This question actually has a complex answer like rewJW explained. Most specialties have some programs that pay stipends, and some programs where you pay tuition. This is true for pedo, endo, perio, ortho, and I think prostho. The programs which pay tuition are normally very competitive to get into, but aren't necessarily the best programs.
The only exception I can think of is OMFS, which all pay stipends (however, the 6yr M.D. programs require you to pay med school tuition for 1-3 years).