There is nothing to stop a dentist carrying out any treatment which they feel they are capable of, but only a qualified orthodontist, has taken the additional years of full-time study at a university, treating cases under experienced supervision to pass examinations and have their expertise recognised by their peers and the government. A specialist orthodontist does not normally carry out other dental treatment like fillings or extractions, so all their time is spent thinking and practicing orthodontics – practice makes perfect!