I think you should add smth to your no answer, smth like that you are a hard-working and very confident that you'll succeed at their dental school. IMO, confidence is the key... and you had to add smth to your simple no b/c they wanted to see how you feel about that and regardless of your score you have a great GPA accumulated over 4 or so years. Show your great sides and deal with weaknesses with confidence with which you'll overcome them all and eventually succeed.
If you DAT is extremely low, then retake if you want... but think why you were invited for the interview, you passed the first round that some people wouldn't pass.
Good luck.
