The ADA and ADEA have lists of all residency programs... most are looking forvariation in student selection, so "out of state" students are ideal.
Select a residency for the program - ask current residents/ and former graduates from your school. Visit programs. Also look at possible locations you may want to practice in, or spend one year in.
We have no dental school in Delaware, so all residents come from out of state dental schools. This year we have some from Maryland, Penn, Temple, UConn, Boston. Last year - Louisville, Virginia, Penn, Temple, Maryland, NJ. We try to blend our program from different schools... it helps the residents exchange ideas and challenges our attendings.
As I said before, we have had a required residency in Delaware for over 60 years (1940) and it has not reduced the # of dentists moving into the state and has improved the competency and level of preactice.