As for the Comprehensive exam, I took mine back in 1996, so i'm almost positive they have changed things since then. However, I do remember putting my fingers in my mouth (sounds weird) to make sure that certain cusps were occluding with specific fossa's, had a ton of those questions. Also, knowing anatomy, grooves, triangular ridges, cusp of carabelli, curve of wilson and spee, difference between class 1, 2, 3, in addition to partial dentures Type 1, 2, 2-modified, 3, 3-mod, etc. If you have the grey Air Force Manual (Vol. 1) and know it, you'll do fine. Know your anatomy/physiology of facial muscles and skeletal bones as well from buccinator, orbiculoris oris, lateral and medial pterygoids, masseter and their functions, also the occipital, parential, sphenoid, zygomatic, max, mand, bone structures. Then don't forget the tooth morphology as well, for instance the periodontal ligament, cementum, cemento-enamel junction, and etc. Wow, I think i just gave myself a migraine.......lol Hope that helps and gets your mind going, don't worry, it's multiple choice, at least when it was when I took it.