I don't this this is accurate at all. When I was at the second look event recently, I talked to multiple people that were still considering other schools. Many were undecided between Baylor and UTSW and also there were plenty of OOS applicants that had acceptances to other great school out of state. I think the vast majority of the movement will occur at the beginning of May since April 30th is the deadline to hold multiple acceptances at schools. So I would not be completely discouraged since I was informed that although it varies from year to year, there is definitely waitlist movement 🙂
Edit: I'm sorry, I thought I saw this on the pre-medical forum! My bad. I'm still hoping some of what I said applies but I can't claim to know anything about how dental school works 😳😳