Abstract:

Objective To evaluate the effectiveness of treatment with maxillary protraction with or without rapid palatal expansion（RPE） for skeletal Class Ⅲ malocclusion in mixed dentition. Methods A total of 31 children with Class Ⅲ malocclusion in mixed dentition were selected, and 15（group A） received maxillary protraction treatment with RPE, the other 16（group B） received maxillary protraction without RPE. Cephalometric films were taken before and after treatment, and traditional and Pancherz analysis were used. Results The average duration of treatment was 10.14 months in group A and 9.77 months in group B respectively（P >0.05）. According to Pancherz analysis, maxillary basal bone moved forwards by 2.99 mm in group A and 3.33 mm in group B respectively（P>0.05）, mandibular basal bone moved backwards by 0.07 mm in group A, while forwards by 0.80 mm in group B（P>0.05）, the overjet increased by 4.51 mm in group A and 6.37 mm in group B respectively（P<0.05）, and the molar relationship improved by 4.97 mm in group A and 4.73 mm in group B respectively（P>0.05）. The effects were clinically satisfactory in the both groups. Lower molar moved forwards by 1.18 mm in basal bone in group A, while backwards by 1.20 mm in group B（P <0.05）. Traditional cephalometric analysis showed no statistic differences between the two groups except that upper incisior showed greater procline in group B than in group A（P<0.05）. Conclusion The study shows that maxillary protraction treatment, with or without RPE, is clinically satisfactory to correct early skeletal Class Ⅲ malocclusion.

Key words: skeletal Class Ⅲ malocclusion, maxillary protraction, rapid palatal expansion, early orthodontic treatment