The use of the Jasper Jumper for the correction of Class II malocclusion in the young permanent dentition.

The effect of the Jasper Jumper in the treatment of Class II, division 1 malocclusions was studied in 26 consecutive 13-25-year-old patients. The median treatment time was 5 months, followed by a median period of observation or retention of 7 months. The effects of the treatment were evaluated from cephalograms taken before the treatment, at the removal of the Jumpers and at the end of the period of observation or retention. The Jumpers brought about a slight retrusion of the maxilla and markedly increased the mandibular prognathism. The maxillary incisors and molars were retruded, and the mandibular incisors and molars protruded. The median correction of the overjet was almost 5 mm and of the molar relationship 3 mm. The intrusive forces of the Jumper resulted in a transient intrusion of the maxillary molars and the mandibular incisors. After the period of retention and observation, the dento-alveolar effects had partially or totally relapsed. The remaining effect contributing most to the correction was the skeletal effect on the mandible, i.e. the increase in mandibular prognathism. The skeletal mandibular effect was the same in younger and older subjects. At the end of observation about 60 per cent of the overjet reduction and 75 per cent of the molar correction remained. The incidence of breakage of the Jumpers was 9 per cent.