4Bjoerk A, Krebs A,Solow B. A method for epidemiologicalregistra- tion of malocclusion [ J ]. Acta Odontol Scand, 1964,22 ( 6 ) : 27 -41.
5Correa-Faria P, Ramos-Jorge ML, Martins-Junior PA, et al. Maloc- clusion in preschool children:prevalence and determinant factors [ J ]. Eur Arch Paediatr Dent, 2014,15 (2) : 89 - 96.
6Carvalho AC, Paiva SM, Scarpelli AC. Prevalence of malocclusion in primary dentition in a population-based sample of Brazilian pre- school children [ J ]. Eur J Paediatr Dent,2011,12 ( 2 ) : 107 - 111.
7Bishara SE, Bayati P, Jakobsen JR. Longitudinal comparisons of dent al arcg changes in normal and untreated Class II , Division 1 subjects and their clinical implications[ J] . Am J Orthod Dent Or- thop,1996,110(5) :483 -489.
8Shaza M, Hammad S, Abeer M sis in Egyptian children [ J ]. et al. Mixed dentition space analy- Pedi Dent J,2010,20 (2): 115 - 121.
9Altherr ER, Koroluk LD, Phillips C. Influence of sex and ethnic tooth-size differences on mixed-dentition space analysis [ J ] Am J Orthod Dentofaeial Orthop, 2007,132 (3) :332 - 329.
