[Principles of epidemiologic studies in orthodontics]

The epidemiological assessment of malocclusion was performed in the past in different ways: registration of composit malocclusion types, of some single individual traits, of many individual traits. In the future the principle should be to register all individual traits of the maldevelopment of the individual dentition in a well defined and reproducible way. Such epidemiological studies are also of importance for the improvement of the differential-diagnosis.