[Displacement of the hinge angle point in a Class II malocclusion; 1 case report during treatment with a Bern activator (an interim report)].

In the context of a global examination of the effects of the activator therapy of Herren in class-II malocclusion, the position of the hinge axis points was studied in a group of 12 consecutive cases (9 boys and 3 girls). The hinger axis was recorded immediately before and in the course of the treatment, using a standardised recording method. After 1 mm change in occlusal relationship, the hinge axis points were located about 2 mm caudally of the tattooed zero point. When the change in occlusal relationship step by step had reached 3, 5 and 7 mm, and even after 6 months of retention, the hinge axis points had moved back by about 1 mm in a cranial direction, but remained still about 1 mm caudally of point zero. In a sagittal direction, a facial dislocation of about 1 mm was found no sooner than after a 6-months retention time. A study on reproducibility was used to ensure the statistical proof of these results.