Abstract:

Objective To assess the outcome of orthodontic treatment with upper jaw or upper and lower jaw extraction for Class Ⅱ division 1 malocclusion using the peer assessment rating（PAR） index. Methods 28 patients with Class Ⅱ division 1 were extracted two first premolars or second premolars of upper jaw, and 24 patients were extracted four premolars of upper and lower jaw N. The PAR was applied on pre-and post-orthodontic treatment dental casts for the fifty-two cases. Results The upper and lower jaw extraction groups had significantly higher initial PAR scores and the weighted PAR total scores（P<0.05）. Although significantly different before treatment, both groups were not statistically different after treatment（P>0.05）. Conclusion The upper and lower jaw extraction cases showed more severe dental displacement. Both treatment can acquire successful results.

Key words: peer assessment rating index, orthodontic extraction, malocclusion, Angle′s Class Ⅱ