5Demir A,Uysal T,Sari Z, et al. Effects of Camouflage Treat ment on Dentofacial Structures in Class II Division 1 Mandib ular Retrognathic Patients[J].Eur J Orthod,2005,27(5) :524- 531.
6Tadic N,Woods M G. Incisal and Soft Tissue Effects of Maxillary Premolar Extraction in Class II Treatment[J].Angle Orthod,2007,77(5) :808-816.
7Piva L M,Brito H H,Leite H R,et ah Effects of Cervical Headgear and Fixed Appliances on the Space Available for Maxillary Second Molars[J].Am J Orthod,2005,128(3) : 366-371.
8Kirjavainen M, Kiriavainen T, Hurmerinta K, et al. Orthopedic Cervical Headgear with an Expanded Inner Bow in Class II Correction[J]. Angle Orthod, 2000,70 (4): 317 -325.
9Bhatia S N, Leighton B C. A Manual of Facial Growth : A Computer Analysis of Longitudinal Cephalometric Growth Data [M]. Oxford:Oxford University Press,1993:244.
10Cangialosi T J, Meistrell M E, Leung M A, et al. A Cephalometric Appraisal of Edgewise Class II Nonextraction Treatment with Extraoral Force[J]. Am J Orthod, 1988,93 (4) : 315- 324.