Like the previous posters said, cosmetic dentistry is not a specialty. Any general dentist is allowed to do any procedure coming out of dental school. You don't need to specialize in ortho to do braces or pediatrics to work with children. However, you're not allowed to call yourself a specialist in any of those fields. Cosmetic dentistry is not recognized as a specialty by the ADA so any dentist can call themselves a cosmetic dentist as soon as they graduate. That said, all it takes to be a cosmetic dentist is the knowledge and the desire to do that type of work. Some schools will teach you all that stuff (my school guarantees to train us in cosmetic procedures and give every student a veneer case) while others won't. If your school is the latter, you can take some courses once you're done to learn how to do those procedures.