Objective:The purpose of this study was to evaluate the effects of activator and FRⅡappliances on growing children with ClassⅡdivision 1 malocclusion.Methods:The material consisted of pre- and post-treatmentmodels and cephalograms of 16 boys and 18 girls. 12 childrenwere treatedwith activators, and 22 were treatedwith FRⅡappliances.Results:Both activator and FR Ⅱappliances can change ClassⅡrelationship to Class I, and significantly reduced ANB angle to a normal range. FRⅡappli- ance statistically increased the dental archwidth of the maxillary, and there was no statistically significant difference between these two groups in changing basal archwidth. The upperincisorswere retracted muchmore in the groups of FRⅡappliance, the axial inclination of the lower incisors was controlled more efficiently in the activator group.Conclusion:Both the activator and the FR Ⅱappliance can correct the ClassⅡmalocclusions efficiently. Selecting correct appliance is very important in the clinical treat- ment.
