I just emailed the schools I was interested in directly.
I recently emailed UPenn last week, and this is what they emailed me back: Hope that this helps:
"Thank you for your interest in our program. Please try to get letters from faculty who know your work and can evaluate your academic performance. Letters do not have to be from science faculty unless it is your major. We need a minimum of two letters. Letters can be sent to us directly or through AADSAS. Please contact our office if you have additional questions.
Sincerely,
Corky Cacas
Director of Admissions
University of Pennsylvania
School of Dental Medicine
240 South 40th Street
Philadelphia, PA 19104-6030
(215) 898-8943
(215) 898-5243 (Fax)
www.dental.upenn.edu"