[Individual response to treatments using Teuscher activator]

Variations in facial growth and dentoalveolar development were studied in a group of 40 patients treated with the Teuscher appliance, a functional appliance which is a combination of an activator and a high-pull headgear. Patients were selected for this study on the basis of an initial Class II Division 1 malocclusion and on being consecutively treated with this appliance. The results showed that in 80% of the patients the maxilla either remained unchanged in it's relationship to the anterior cranial base (NSL) or became more retrusive during the treatment period. The mandible in 70% of the patients became more prognathic, only in four cases did the mandible become slightly more retrognathic. The analysis further showed that no statistically significant change occurred in the inclination of the mandible during treatment. Correlation analysis of the association between pretreatment mandibular plane angle and the changes during treatment showed no association. The dentoalveolar changes were characterized by retroclination of the maxillary incisors in 90% of the patients which occurred in spite of the torque springs, intended to maintain the inclination of these teeth. In contrast, the mandibular incisors on average showed no statistically significant change during treatment. This may be attributed to the capping of these teeth. Analysis of the association between the pretreatment inclination and the change during treatment of the mandibular incisors showed an inverse relationship. Mandibular incisors, that initially were proclined, tended to become more upright which is in contrast to previous studies indicating that functional appliance treatment generally increases the inclination of these teeth. The results of this study suggest that the correction of the skeletal component of the Class II malocclusion with the Teuscher appliance in most instances takes place by restriction of forward development of the maxilla in combination with downward-forward growth of the mandible, but with wide individual variations. The control of the incisor inclination in the maxilla with this appliance, however, is not adequate and further development in this area is needed. In contrast, the control of the lower incisors by capping helps effectively control these teeth against undesirable proclination during treatment.