Table 2 Results of intergroup comparability at pretreatment (T1) posttreatment (T2) and postretention (T3) (independent t tests)

Maxillary dental casts measurements

Little's irregularity index

6.84 (2.97)

8.40 (4.10)

0.195

0.37

(0.68)

0.12

(0.41)

0.154

1.55

(1.95)

2.71

(2.38)

0.111

3–3 width

34.20 (2.50)

34.57 (2.25)

0.650

34.93

(1.76)

34.8

(1.86)

0.922

33.02

(4.02)

34.02

(2.10)

0.303

5–5 width

44.79 (2.66)

43.81 (2.18)

0.218

43.46

(1.64)

42.7

(1.97)

0.216

41.96

(2.41)

41.55

(2.31)

0.591

6–6 width

49.39 (2.62)

49.09 (2.10)

0.689

48.28

(1.43)

47.79

(2.45)

0.473

47.51

(2.40)

47.37

(2.76)

0.877

Arch length

27.89 (2.71)

28.08 (2.64)

0.821

22.71

(3.51)

22.0

(2.91)

0.537

20.11

(2.32)

21.18

(1.62)

0.089

Arch perimeter

70.66 (5.98)

72.16 (5.29)

0.404

61.91

(3.06)

62.9

(2.67)

0.254

58.86

(3.72)

60.47

(3.49)

0.170

Mandibular dental casts measurements

Little's irregularity index

3.31 (2.10)

9.94 (2.65)

0.000*

0.58

(0.97)

0.48

(0.82)

0.720

3.67

(2.11)

4.60

(3.05)

0.292

3–3 width

26.53 (2.01)

25.73 (2.24)

0.253

26.7

(1.33)

27.15

(1.38)

0.345

24.23

(2.70)

25.36

(2.32)

0.160

5–5 width

39.43 (3.17)

37.17 (2.20)

0.011*

35.40

(1.92)

35.51

(1.73)

0.846

34.48

(2.48)

34.06

(2.04)

0.551

6–6 width

44.05 (2.01)

42.71 (2.37)

0.071

40.7

(1.43)

40.1

(2.53)

0.379

41.78

(2.91)

40.38

(2.89)

0.140

Arch length

23.11 (1.87)

22.72 (2.52)

0.595

17.87

(1.93)

18.2

(2.33)

0.608

15.58

(1.76)

16.93

(1.98)

0.032*

Arch perimeter

62.20 (5.53)

63.76 (3.11)

0.255

52.76

(3.03)

53.6

(2.27)

0.311

49.04

(3.11)

50.47

(3.35)

0.180