Well
@jweaver421 said above they sent a personal check and had no problems but I was going to email them to verify this and will get back to you on it.
Haha yes I was thinking the same thing... wtf do they want you to do? I just went and checked their website and it says:
"After completing the AADSAS application, the student should forward a $45 processing/application fee to the Marquette University School of Dentistry"
So I'm assuming you can go ahead and send the fee after submitting your AADSAS application and don't have to wait until you hear from the Admissions Office.