Abstract:

Objective　To investigate morphologic changes of Angle classⅡand skeletal classⅠpatients during pendulum and straight wire appliances treatment and to analyze the mechanism of this treatment protocol.Methods　10 patients with Angle classⅡand skeletal classⅠmalocclusion 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 in- cluding skeletal, dental and soft tissue relationships.Results　Differences between theT1 andT2 meanswere 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 betweenT1 andT3 in respect saggital position and angulation of the maxillarymolars (P>0·05). Onlythe mesial movement of lowerfirstmolars and upper and lower jawswere sig- nificant (P<0·01) duringthewhole treatment. No upper second molar impactionwas detected aftertreatment.Conclusion　The upper molars distalization could be achieved by pendulum appliance. The classⅠmolar relationship could be obtained by the dif- ferential growth of jaws and the differential movement of upper and lower molars.

Key words: pendulum appliance, straight wire appliance, Angle’s classⅡmalocclusion