OBJECTIVETo investigate morphologic changes of Angle class II and skeletal class I patients during pendulum and straight wire appliances treatment and to analyze the mechanism of this treatment protocol.

METHODS10 patients with Angle class II and skeletal class I malocclusion were recruited. The lateral cephalometric radiographs were evaluated to determine if there were significant differences among pre-treatment (T1), after molar distalization (T2), and post-treatment (T3) variables including skeletal, dental and soft tissue relationships.

RESULTSDifferences between the T1 and T2 means were significant for distal movement and distal angulation of the maxillary molars (P < 0.01), mesial angulation of the maxillary incisors (P < 0.05), mesial movement of the maxilla (P < 0.01) . There were no significant changes between T1 and T3 in respect saggital position and angulation of the maxillary molars (P > 0.05) . Only the mesial movement of lower first molars and upper and lower jaws were significant (P < 0.01) during the whole treatment. No upper second molar impaction was detected after treatment.

CONCLUSIONThe upper molars distalization could be achieved by pendulum appliance. The class I molar relationship could be obtained by the differential growth of jaws and the differential movement of upper and lower molars.