A BIG registration is a legal, online and public register to which you need to be subscribed in order to be able to work independently as a healthcare professional in the Netherlands. BIG stands for Beroepen in de Individuele Gezondheidszorg (Professions in Individual Healthcare), and when your registration is complete, you receive a registration number that allows you to practice your profession.
As a foreign dentist, you are obligated to pass the language exam for medical professionals as a requirement to be registered in the BIG.