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Table 3 Descriptive statistics and statistical analysis of the treated patients at T3 and the control groups

From: Anchorage onto deciduous teeth: effectiveness of early rapid maxillary expansion in increasing dental arch dimension and improving anterior crowding

  Groups Comparison among groups
  Treated group Children with a lateral cross-bite Children without a lateral cross-bite Adolescents with a normal occlusion p value
n = 20 n = 20 n = 20 n = 20  
Mean age (SD), years 9.8(1.3) 9.0(0.9) 9.2(1.1) 14.3(2.4)  
Inter-canine width      
 mean (SD), mm 32.2(2.0) 30.3(3.1) 31.8(2.0) - 0.0353*
 95 % CI 31.3 to 33.1 28.8 to 31.7 30.9 to 32.7   
Inter-molar width      
 mean (SD), mm 49.6(2.3) 44.5(2.4) 47.9(2.9) 50.6(2.8) <0.001
 95 % CI 48.5 to 50.6 43.3 to 45.6 46.5 to 49.2 49.4 to 52.1  
Inter-molar depth      
 mean (SD), mm 29.8(1.7) 31.8(2.2) 32.1(2.0) 29.0(1.6)  
 95 % CI 29.0 to 30.6 30.8 to 32.9 31.2 to 33.0 28.3 to 29.8 <0.001
Irregularity index      
 median (Iqr)§, mm 2.4(1.4) 3.2(2.9) 4.0(4.0) - 0.0094
  1. *One-way ANOVA (F (2,57) = 3.55; power of the test = 98 %; rho = 0). Significant pair differences (Bonferroni test): treated group vs children with a lateral cross-bite (p = 0.042). One-way ANOVA (F (3,76) = 21.60; power of the test = 100 %; rho = 0). Significant pair differences (Bonferroni test): treated group vs children with a lateral cross-bite (p < 0.001) and adolescents with a normal occlusion vs both children with a lateral cross-bite (p < 0.001) and children without a lateral cross-bite (p = 0.005). One-way ANOVA (F (3,76) = 12.86; power of the test = 99 %; rho = 0). Significant pair differences (Bonferroni test): treated group vs both children with a lateral cross-bite (p = 0.006) and children without a lateral cross-bite (p = 0.001); adolescents with a normal occlusion vs both children with a lateral cross-bite (p < 0.001) and children without a lateral cross-bite (p < 0.001). §Iqr is interquartile range. ǂKruskal-Wallis equality-of-populations rank test. Significant pair differences (two-sample Wilcoxon rank-sum test): treated patients vs children with a lateral cross-bite (p = 0.0094) and children without a lateral cross-bite (p = 0.0080)