Late Results of Activator-Treatment: A cephalometric study

Abstract

The purpose of this study was to analyse cephalometrically the long-term effect of Activator treatment on the dentofacial skeleton in 50 consecutively treated cases of postnormal and prenormal occlusion. Comparisons of dentofacial form between successful and unsuccessful cases were performed. The results of the study showed that the sagittal relationship between the jaws became normal in postnormal and prenormal cases during Activator treatment. The effect was achieved mainly by reciprocal dentoalveolar changes of the maxilla and mandible supported by a retardation of the forward growth of the maxilla in Class II cases and a stimulation of the forward growth of the maxilla in Class III cases. The normal downward-forward growth of the mandible appeared unaffected. The effect of Activator treatment on the vertical growth of the jaws was a significant increase in lower face height (bite-raising). No tendency to induce a harmful posterior growth rotation of the mandible was noted. Before treatment there was no highly significant difference in the morphology of the dentofacial skeleton between successfully and unsuccessfully treated Activator cases, except for the basal relationship between the jaws (ss-n-sm) which was larger in the successful cases. It would rather appear that good cooperation, high growth intensity and a favourable growth pattern of the patient together with a well constructed appliance is of decisive importance for a successful result of treatment.