[50 years of recurrence]

50 years of practice in orthodontics! The calling-up of the past raises old conceptions of orthodontics, full of illusions on its real possibilities and placed under the dictatorship of Pont's index. Some years later, the american technics were brought to France, and progressively took advantage on functional methods. From 1981, a series of studies conducted by Little shows the frequency of relapses after excellent treatments. It is clear that orthodontics could not survive if it was confirmed that it has only a temporarily effect. Different causes of relapses are examined: some particular effects of facial growth, the use of over-correction and pre-formed materials, the lack of occlusal equilibration by reshaping, the neglecting of periodontal reactions, the incorrect application of rules of contention. But the fundamental cause of instability of treatments observed by Little, is it not that these treatments have been performed in agreement with the concepts of the years 1950-1960, that is to say more determined by a geometrical representation of the face, and a mechanical conception of the treatment, rather than been guided by a good comprehension of the physiology of the patient?