I asked several program directors regarding 6 year programs for Advanced standing graduates. First You must be US citizen or PR . whether you will get accepted with only 2 year advanced standing ( no first 2 year DS and US Undergraduate degree) or not Depends on the program you are applying to. Most of them require Full US BA/ BS and Full DDS. However, some programs will take advanced standing graduates if they are competitive and strong applicant. 6 year programs that have no problem according to PD respones are UIC , Cornell , LLU , UCLA and one of Texas program ( houston program i guess) and other programs that i don't remember right now. Some PD explained AS applicants are at disadvantage but they are still eligible to apply. At some Omfs programs , omfs department has upper hand in selecting applicants with little medical school restrictions. But that is not the case for for oms program affiliated with prestigious med school like MGH . where applicant has to be accepted by both med school and oms program. That the case for 6 year program. However ,Most 4 year programs are ok with AS applicant.