Hi! greeny,
the exam pattern has sure changed a lot since 2006.The exam was much more easier comparitively to what it is right now.Then,the questions used to be much more straight forward.But now its all twisted up.Kinda like most of the questions make you sweat,confused,think real real hard.I was able to corner the choices to two .That was easy.But the last two choices were really something.Both of those choices were so close.There are clinical vignettes.It starts towards the end of the first session if i remember well and after the one hour break for the next 80 questions or so it is just these clinical cases.I think there are 8 or 10 clinical vignette cases.God! i forgot.Well! the pilot paper should give you an idea as to what it is like right now.But believe me the real ADA exam is much difficult than the pilot 2004 paper.So be prepared well! When i took the exam in dec 2009,i felt the questions that were asked were so much in depth.They sure check your basics.I mean i never felt that way for the 2006 paper that i had taken long ago.Then as you know its all jumbled up.There is no different section to each subject.Just one chance.Use it wisely!Any help please feel free to ask.