I actually got my BostonU interview w/o LOR. I sent all my LOR directly to schools with predental committee letter in early June. And BU somehow didn't recieve one (mails get lost I guess).
I actually found out about this on the interview day. My interviewer told me that my file is missing LOR and committee letter. So I checked with the secretary after my interview, and she said BU never recieved it, and I should submit another copy ASAP.
So, I guess you can get interview w/o LOR in some schools.