Who would be a member of the American Dental Association is it a retired dentist a dentist student or a dentist patient?

A retired dentist. Just because they retire doesn't mean they lose their accreditation. Those are professional boards that certify you meet their requirements. You've met the requirement. A dental student is still a student and therefore doesn't qualify for accreditation as they're not licensed dentists. Lastly, why would the patient have an accreditation unless they're a dentist themselves?