Well this is a tricky question. A simple way to look at it is an orthodontist is a dentist but a dentist is not necessarily an orthodontist. A dentist focuses on a more broad spectrum of oral health. They are the MOST essential part of your oral health! An orthodontist first must complete dental school and become a dentist. Only after they are a dentist can they apply to an accredited orthodontic residency program. One they have completed their 2-3 year program they can then call themselves an orthodontist. Upon graduation orthodontists generally only focus on the practice of orthodontics which makes them the experts of their field not only from their education but also their immersion in the sole practice of orthodontics.