Prettygirl, for those who decide to utilize this option, there chances are excellent. As in near 100% acceptance rate.
Analyze it for a moment. When applying to dental school, the schools much prefer candidates who shadowed dentists or even worked in dentistal offices or were assistants, etc. This is because such applicants have a very realistic idea of what the dental profession involves, and their experiences will bolster them throughout their education.
Post-grad education isn't any different. Specialty programs will gladly accept decent candidates if they have practiced for a couple of years. These applicants have first-hand experience. Say they are applying to an endo program. Chances are they have chosen endo because they've seen some endo in their office and they've done what they could handle and loved it! They have real-world expertise and experience, which is something that most applicants to specialty programs lack. Dental school is NOT the practice of dentistry in the real world (obviously).
Those who practice then apply to specialty programs are rarely denied.