[I. Borderlines between orthodontics and oral surgery]

The division of responsibility between orthodontics and surgery is determined by the severity of deviation in facial development. In young, growing patients the border cannot be always determined at first. As a result there is an area of overlap whose extent is primarily influenced by the developmental age and cooperativeness of the patient, as well as by the cephalofacial type and therefore growth pattern. When the indications are for a surgical treatment of the facial structures, thre is a fundamental change in the orthodontic goals. One of the first steps of a joint planning must be the determination of which facial structures, in which directions and to what extent, must be the determination of which facial structures, in which directions and to what extent, should be surgically moved. The proposed, but not yet realised, skeletal outline is the matrix for the orthodontic preparation. The presurgical efforts include, at a minimum, the removal of occlusal barriers that would interfere with the surgical displacement of the skeletal units and at a maximum, the anticipating coordination of both arches so that immediately after surgery perfect occlusal harmony is reached.