take it from me (just had my michigan interview this past friday), it is one of the MOST fun experiences I have ever had at a dental school lol.
Those MMIs are not there to harass you with your answers, you can say WHATEVER you feel is right answer, all they do is listen to you, and sometimes ask you a few questions here and there to get you to think more thouroughly. Out of the 10 interviwers, I say I impressed 7 AT LEAST, the other 3... well, I know I screwed up one and the other 2 are a toss up lol
But seriously, there is NOTHING to worry about. The case scenarios DESCRIBE EVERYTHING to you.... so for example, the scenario would have a title "Amalgam Fillings" ... the scenario would describe what amalgam is, what are some of the political views that are for it, what are some that are against it, and then the question will ask you "what do you think are the pros and cons based on this reading"..... its very straight forward and like I said before, there is no right/wrong answer here.