Effect of cervical anchorage studied by the implant method.

Two groups each of 10 patients with distal molar relation, identical as regards dental stage, were treated, with the Kloehn headgear only, for eight months. As related to the occlusal plane, the extraoral arch of the headgear was tilted 20 degrees upwards in one group, and 20 degrees downwards in the other. By the implant method, it is possible to distinguish between growth changes and intramaxillary tooth movements. The local influence on the tipping, mesiodistal change in position and extrusion of the first upper molar was measured, and facial growth pattern recorded. In the group with upward tilt of the extraoral arch, only slight tooth movements occurred, but the entire maxillary complex shifted backwards and downwards in relation to the anterior cranial base during the period of treatment, resulting in an approach to normal molar relationships. In the group with downward tilt of the extraoral arch, greater intramaxillary tooth movements were measured; in particular, a distal tipping of the first molar occurred. In these patients no influence on the maxillary complex could be measured during the period of treatment.