[The effectiveness of asymmetric extraction in treatment of Class II division 1 malocclusions].
OBJECTIVE
To analyze hard and soft tissue profile changes before and after asymmetric extraction treatment of Angle Class II division 1 malocclusion.


METHODS
Thirty patients of Angle Class II division 1 malocclusions (11 males, 19 females, average age 13.6 years) were divided into two groups according to their extraction approach. In asymmetric extraction group, 2 first maxillary premolars and 1 first mandibular premolar were extracted. In the control group, all 4 first premolars were extracted. Lateral cephalometric radiographs were taken before and after treatment to compare hard and soft-tissue changes between the two groups, and the cephalometric measurements were analysed by SAS6.12 software package for independent sample t test.


RESULTS
In comparison of the changes between the two groups, significant differences in dentoskeletal measurements were observed with NAPog, SNA, ANB, MP-SN and with the inclinations of the upper and lower incisors (P<0.01). Significant differences in soft-tissue changes were also observed in the thickness of upper lip, the Z angle (P<0.01) and the nasolabial angle (P<0.05). Compared to the profile before treatment,only inclination of lower incisors changed significantly after treatment (P<0.01).


CONCLUSIONS
Asymmetric extractions is feasible in treatment of Class II division 1 malocclusions evidenced by retractions of both upper and lower incisors and improves sagittal soft-tissue profile. Supported by Research Fund of Science and Technology Commission of Shanghai Municipality (Grant No.08DZ2271100).
Chen
Wei
W
Department of Orthodontics, College of Stomatology, Ninth People's Hospital, Shanghai Jiao Tong University School of Medicine, Shanghai Key Laboratory of Stomatology. Shanghai 200011, China. iam.chenwei@yahoo.com.cn
Chen
Rong-jing
RJ
Pan
Xiao-gang
XG
Yu
Quan
Q
Hu
Zheng
Z
Shen
Gang
G
D000293:Adolescent; D001641:Bicuspid; D002508:Cephalometry; D005260:Female; D006801:Humans; D008046:Lip; D008297:Male; D008310:Malocclusion; D008312:Malocclusion, Angle Class II; D014081:Tooth Extraction; D016896:Treatment Outcome