Abstract: Objective: To compare the changes of soft and hard tissue profiles of the adolescent patients with class Ⅱ division 1 malocclusion between before and after treated with two different kinds of tooth extraction methods, and to provide the reference for clinical treatment. Methods: A total of 60 adolescent patients with class Ⅱ division 1 malocclusion were included,and they were divided into 44/44 group(n=30) and 44/55 group(n=30) based on different kinds of tooth extraction methods. Four first premolars of the patients in 44/44 group were extracted and 2 maxillary first premolars and 2 mandibular second premolars of the patients in 44/55 group were extracted.The measurement indexes of pre-treatment(T1) and post-treatment(T2) and their difference values(T2-T1) of soft and hard tissues of the adolescent patients were detected by lateral cephalometric radiographs. Results: As for the hard tissue,compared with before treatment,the Overjet,SNA,ANB,U1-NA,distance of U1-NA,U1-SN,NA-PA,and A-NP of the adolescent patients in two groups after treatment were decreasd (P<0.01),and U1-L1 and Pog-NB were increased (P<0.05 or P<0.01); as for the soft tissue, compared with before treatment, the H angle, UL-SnPg', LL-SnPg', UL-ELine, LL-ELine, and Sn-HLine of the adolescent patients in two groups after treatment were decreased(P<0.05 or P<0.01); B'LL-FH was increased(P<0.01);there were no significant differences in the difference values(T2-T1) of measurement indexes in the soft and hard tissues of the adolescent patients in two groups (P>0.05). Conclusion: The changes of soft and hard tissue profiles of the adolescent patients after treated with two different kinds of tooth extraction methods are not significant.

Key words: class Ⅱ division 1 malocclusion, extraction, soft and hard tissue profile