Table 9 Comparison between chronological age and estimated age by EGY II (upper jaw) in group I (n = 1000) at different class intervals

Mean ± SD

Mean ± SD

Mean ± SD

149

6.43 ± 0.22

6.82 ± 0.52

0.39 ± 0.57

8.351^*

 < 0.001^*

145

7.45 ± 0.24

7.82 ± 0.83

0.37 ± 0.82

5.384^*

 < 0.001^*

219

8.47 ± 0.26

8.84 ± 0.85

0.37 ± 0.82

6.615^*

 < 0.001^*

106

9.60 ± 0.33

9.67 ± 0.91

0.07 ± 0.95

0.737

0.463

258

10.48 ± 0.26

10.10 ± 0.63

-0.38 ± 0.69

8.899^*

 < 0.001^*

87

11.45 ± 0.26

10.85 ± 0.64

-0.60 ± 0.54

10.305^*

 < 0.001^*

36

12.42 ± 0.25

11.10 ± 0.53

-1.33 ± 0.56

14.176^*

 < 0.001^*