I am a 3rd year dental student at USC which is probably 90% PBL. Although we had cases regarding topics related to our upcomng simulation labs, our learning would be supplemented by the occasional 1 hr lecture. The lectures were much more effective that the cases for learning how to do endo, or cut a crown prep, or fundamentals and indications for bridge design...etc. I think that the general consensus among my classmates was that PBL for dental related topics was ineffective and confusing, however the PBL cases relating to physiology, pathology, anatomy etc were very effective ways to learn.
Hope this helps.