Trainee dental nurse interview question "Why do you want to be a Dental nurse"?

Hey guys, got interview in few hours and am struggling with this question or similar question the interviewers might ask "why do you want to be a dental nurse?". I'm struggling because..well, this option is just a fall back really..though i am interested in the whole nursing part..but yeh..what can i say? lol Also, if anybody had token an interview for trainee dental nurse before, what else do they do? my friend said they get you to do a short exam for maths and english and also short practical work..thanks