7Lima Filho RM, Lima AL, de oliveira Ruellas AC. Longitudinal Study of anteroposterior and vertical maxillary changes in skeletal class Ⅱ patients treated with kloehn cervical headgear [ J ]. Angle Orthod, 2003,73 : 187 - 3293.
8Ghafari J, Shofer FS, Hunt U, et al. Headgear Versus function regulator in the early treatment of Class Ⅱ , Division 1 malocclusion: A randomized clinical trial [ J ]. Am J. Orthod entofacial Orthop,1998,133:51 -61.
9Mantysaari R, kantomaa T, pirttiniemi P, et al. The effects of early headgear treatment on dental arches and craniofacial morphology: a report of a 2 year randomiztd study[J]. Eur J Orthod,2004(26) :59 -64.
4SPENCER P,BOHATY B,HAYNES JI,et al.Change in dental treatment needs in an urban pediatric population,1977 to 1987[J].ASDC J Dent Child,1989,56:463-466.
4Kim YH. The versaticity and effectiveness of the multiloop edgewise archwire in treatment of various malocclusion [J]. World J orthod,2001,7(4) :147 - 150.
5Sugawara J. Long - term effect of chin cap therapy on skeletal profile in mandibular pronathism [ J]. Am J orthod,1990,98(2) :127 - 128.
6Tollar. Craniofacial changes induced by early functional trealment of class malocclusion [ J ]. Am J orthod, 1996, 109(6) :310 -312.
