Personally, it is like a job interview. They want to see if you
a) can present yourself
b) know a thing or two about hygene
c) can talk, and carry on a conversation
d) know how to listen (very important in this profession)
e) SHOW INTEREST in anything that they are saying
f) goes with e) the fact that u ask so many questions shows that u are really serious about wanting to go to dental school, and to their school especially
g) and last but not least, if u didn't get a chance to write something on the applicaiton, or would like them to know when considering your application, then that is the time to say it.
If you thought that all of your interviews went well, then you have nothing to worry about. You were probably articulate enough, that being questioned or talked to didn't phase you much. In my group I had few ppl that I personally would never allow near my face and my teeth.....
If u had four interviews already, u have nothing to worry about!