4Mavroskoufis F. Nasal width and incisivepapilla as guidesfor the selection and arrangement of maxillary anterior. J Prosthet ent, 1981,45: 592-609.
5Olayinka D, Otuyme , Joe H, et al. A comparison of crown size dimensions of the permanent teeth in a Nigerianauet and a british population[J ]. European journal of Orthodontics, 1996,18: 623 - 626.
6Margherita Santoro, Michacl E, Victor Ar, et al. Mesiodistal crown dimensions and tooth size discrepancy of the pemanent dentition of dominican American[ J ]. Angle orthod, 2000,70: 303 - 307.
7Ta AT, ling JYK , Hagg U. Tooth-size discrepancies among different occlusion groups of southern Chinese children [J]. Am J Orthod,2001,120:556 - 558.